Three-dimensional limit variation analysis on the ultimate pullout capacity of the anchor cables based on the Hoek-Brown failure criterion

Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC)of anchor cables in most previous research.This study focuses on a more comprehensive combination failure mode that consists of bond failure of an anchorage body and failure of an anchored rock mass.The three-dimensional ultimate pullout capacity of the anchor cables is calculated based on the Hoek-Brown failure criterion and variation analysis method.The numerical solution for the curvilinear function in fracture plane is obtained based on the finite difference theory,which more accurately reflects the failure state of the anchor cable,as opposed to that being assumed in advance.The results reveal that relying solely on a single failure mode for UPC calculations has limitations,as changes in parameter values not only directly impact the UPC value but also can alter the failure model and thus the calculation method.

Effects of cement-enhanced soil on the ultimate lateral resistance of composite pile in clayey soil

The composite pile consisting of core-pile and surrounding cement-enhanced soil is a promising pile foundation in recent years.However,how and to what extent the cement-enhanced soil influences the ultimate lateral resistance has not been fully investigated.In this paper,the ultimate lateral resistance of the composite pile was studied by finite element limit analysis(FELA)and theoretical upper-bound analysis.The results of FELA and theoretical analysis revealed three failure modes of laterally loaded composite piles.The effects of the enhanced soil thickness,strength,and pile-enhanced soil interface characteristics on the ultimate lateral resistance were studied.The results show that increasing the enhanced soil thickness leads to a significant improvement on ultimate lateral resistance factor(N P),and there is a critical thickness beyond which the thickness no longer affects the N P.Increasing the enhanced soil strength induced 6.2%-232.6%increase of N P.However,no noticeable impact was detected when the enhanced soil strength was eight times higher than that of the natural soil.The maximum increment of N P is only 30.5%caused by the increase of interface adhesion factor(a).An empirical model was developed to calculate the N P of the composite pile,and the results show excellent agreement with the analytical results.

Development of mathematically motivated hybrid soft computing models for improved predictions of ultimate bearing capacity of shallow foundations

Ultimate bearing capacity(UBC)is a key subject in geotechnical/foundation engineering as it determines the limit of loads imposed on the foundation.The most reliable means of determining UBC is through experiment,but it is costly and time-consuming which has led to the development of various models based on the simplified assumptions.The outcomes of the models are usually validated with the experimental results,but a large gap usually exists between them.Therefore,a model that can give a close prediction of the experimental results is imperative.This study proposes a grasshopper optimization algorithm(GOA)and salp swarm algorithm(SSA)to optimize artificial neural networks(ANNs)using the existing UBC experimental database.The performances of the proposed models are evaluated using various statistical indices.The obtained results are compared with the existing models.The proposed models outperformed the existing models.The proposed hybrid GOA-ANN and SSA-ANN models are then transformed into mathematical forms that can be incorporated into geotechnical/foundation engineering design codes for accurate UBC measurements.

树脂纳米陶瓷Lava Ultimate髓腔内固位冠修复老年脑卒中病人短冠磨牙的疗效观察

目的探讨树脂纳米陶瓷Lava Ultimate髓腔内固位冠修复老年脑卒中病人短冠磨牙的疗效。方法收集研究2018年3月至2021年10月北京市大兴区医院老年脑卒中短冠磨牙病人124例,根据修复方案分为两组,采用紫荆氧化锆全瓷冠修复治疗的61例病人为对照组,采用树脂纳米陶瓷Lava Ultimate髓腔内固位冠修复治疗的63例为观察组。采用改良美国公共卫生机构(United States public health service,USPHS)标准比较两组修复后6、12个月修复效果、微渗漏分级、并发症发生率、修复前、修复后12个月口腔健康影响程度量表中文版(OHIP-14)评分及修复后12个月李克特量表(Likert scale)评分。结果修复效果:修复后12个月观察组边缘密合度、颜色匹配度、修复体折裂、牙体完整性、继发龋合格率分别为93.65%(59/63)、93.65%(59/63)、96.83%(61/63)、96.83%(61/63)、95.24%(60/63),均高于对照组[80.33%(49/61)、81.97%(50/61)、83.61%(51/61)、81.97%(50/61)、83.61%(51/61)](P<0.05);微渗漏分级:两组修复后6、12个月微渗漏分级比较,差异无统计学意义(P>0.05);并发症:观察组并发症发生率3.17%(2/63)低于对照组14.75%(9/61)(P<0.05);口腔健康相关生活质量:修复后12个月观察组OHIP-14量表功能限制、生理疼痛、心理不适、生理障碍、心理障碍、社交障碍评分分别为(1.89±0.57)分、(2.03±0.62)分、(0.92±0.30)分、(0.53±0.18)分、(0.42±0.10)分、(0.63±0.25)分,均低于对照组[(2.55±0.74)分、(2.73±0.88)分、(1.29±0.27)分、(0.74±0.26)分、(0.31±0.13)分、(0.89±0.20)分](P<0.05);修复效果满意度:修复后12个月观察组修复效果自我评估、并发症满意度、生活质量满意度评分依次为(4.62±0.39)分、(4.25±0.44)分、(4.57±0.40)分,均高于对照组[(4.12±0.35)分、(3.86±0.35)分、(4.03±0.46)分](P<0.05)。结论树脂纳米陶瓷Lava Ultimate髓腔内固位冠修复应用于老年脑卒中病人短冠磨牙,修复效果良好,有助于降低并发症发生率,提高口腔健康相关生活质量,改善修复效果满意度。

New design equations for estimation of ultimate bearing capacity of shallow foundations resting on rock masses

Rock masses are commonly used as the underlying layer of important structures such as bridges, dams and transportation constructions. The success of a foundation design for such structures mainly depends on the accuracy of estimating the bearing capacity of rock beneath them. Several traditional numerical approaches are proposed for the estimation of the bearing capacity of foundations resting on rock masses to avoid performing elaborate and expensive experimental studies. Despite this fact, there still exists a serious need to develop more robust predictive models. This paper proposes new nonlinear prediction models for the ultimate bearing capacity of shallow foundations resting on non-fractured rock masses using a novel evolutionary computational approach, called linear genetic programming. A comprehensive set of rock socket, centrifuge rock socket, plate load and large-scaled footing load test results is used to develop the models. In order to verify the validity of the models, the sensitivity analysis is conducted and discussed. The results indicate that the proposed models accurately characterize the bearing capacity of shallow foundations. The correlation coefficients between the experimental and predicted bearing capacity values are equal to 0.95 and 0.96 for the best LGP models. Moreover, the derived models reach a notably better prediction performance than the traditional equations.

Experimental and Numerical Investigation on High-Pressure Centrifugal Pumps:Ultimate Pressure Formulation,Fatigue Life Assessment and Topological Optimization of Discharge Section

A high percentage of failure in pump elements originates from fatigue.This study focuses on the discharge section behavior,made of ductile iron,under dynamic load.An experimental protocol is established to collect the strain under pressurization and depressurization tests at specific locations.These experimental results are used to formulate the ultimate pressure expression function of the strain and the lateral surface of the discharge section and to validate finite element modeling.Fe-Safe is then used to assess the fatigue life cycle using different types of fatigue criteria(Coffin-Manson,Morrow,Goodman,and Soderberg).When the pressure is under 3000 PSI,pumps have an unlimited service life of 107 cycles,regardless of the criterion.However,for a pressure of 3555 PSI,only the Morrow criterion denotes a significant decrease in fatigue life cycles,as it considers the average stress.The topological optimization is then applied to the most critical pump model(with the lowest fatigue life cycle)to increase its fatigue life.Using the solid isotropic material with a penalization approach,the Abaqus Topology OptimizationModule is employed.The goal is to reduce the strain energy density while keeping the volume within bounds.According to the findings,a 5%volume reduction causes the strain energy density to decrease from 1.06 to 0.66106 J/m^(3).According to Morrow,the fatigue life cycle at 3,555 PSI is 782,425 longer than the initial 309,742 cycles.

Lava Ultimate优韧瓷高嵌体修复无髓后牙牙体缺损的临床分析

目的探讨Lava Ultimate优韧瓷高嵌体修复无髓后牙牙体缺损的临床效果。方法选取本院于2019年3月至2022年3月收治的无髓后牙牙体缺损患者为研究对象,采用随机排列法分为对照组和研究组。对照组45例患者Ceramage聚合瓷高嵌体修复,研究组45例患者则予以Lava Ultimate优韧瓷高嵌体修复,比较治疗前和治疗6周后两组患者菌斑指数(PLI)和牙龈指数(GI)等指标变化;同时采用牙齿咬合力测试仪与沉重法评估患者治疗前后的咬合力与咀嚼功能,统计两组满意度。结果治疗前,两组PLI、GI无显著差异(P>0.05),治疗后,研究组PLI、GI低于对照组,两组差异显著(P<0.05);治疗前两组患者牙齿功能相比,差异无统计学意义(P>0.05)。相较于对照组,研究组患者治疗后咬合力、咀嚼功能指标均明显上升,差异有统计学意义(P<0.05);研究组病患牙齿外观总满意度高于对照组(P<0.05)。结论Lava Ultimate优韧瓷高嵌体修复无髓后牙牙体缺损的的效果满意,能有效提升患者咀嚼功能,维持良好的牙龈状态,抑制牙龈沟炎性因子生成,缓解局部炎症,改善牙功能,但其也存在固有缺点,如价格昂贵、操作复杂等,需要临床根据患者的实际情况合理选择最佳修复材料。

The Ultimate Anti-Seismic Design Method

The design mechanisms and methods of the invention are intended to minimize problems related to the safety of structures in the event of natural phenomena such as earthquakes, tornadoes, and strong winds. It is achieved by controlling the deformations of the structure. Damage and deformation are closely related concepts since the control of deformations also controls the damage. The design method of applying artificial compression to the ends of all longitudinal reinforced concrete walls and, at the same time, connecting the ends of the walls to the ground using ground anchors placed at the depths of the boreholes, transfers the inertial stresses of the structure in the ground, which reacts as an external force in the structure’s response to seismic displacements. The wall with the artificial compression acquires dynamic, larger active cross-section and high axial and torsional stiffness, preventing all failures caused by inelastic deformation. By connecting the ends of all walls to the ground, we control the eigenfrequency of the structure and the ground during each seismic loading cycle, preventing inelastic displacements. At the same time, we ensure the strong bearing capacity of the foundation soil and the structure. By designing the walls correctly and placing them in proper locations, we prevent the torsional flexural buckling that occurs in asymmetrical floor plans, and metal and tall structures. Compression of the wall sections at the ends and their anchoring to the ground mitigates the transfer of deformations to the connection nodes, strengthens the wall section in terms of base shear force and shear stress of the sections, and increases the strength of the cross-sections to the tensile at the ends of the walls by introducing counteractive forces. The use of tendons within the ducts prevents longitudinal shear in the overlay concrete, while anchoring the walls to the foundation not only dissipates inertial forces to the ground but also prevents rotation of the walls, thus maintaining the structural integrity of the beams. The prestressing at the bilateral ends of the walls restores the structure to its original position even inelastic displacements by closing the opening of the developing cracks.

Lava Ultimate髓超嵌体对磨牙缺损根管修复美观度及实用性价值

目的:探讨Lava Ultimate髓超嵌体对磨牙缺损根管修复美观度及实用性价值。方法:选取2020年3月至2021年4月在古田县医院接受磨牙缺损根管治疗的患者178例(204颗磨牙)作为研究对象,按照入院先后顺序分为对照组和观察组,各89例(102颗磨牙)。对照组以Vita Tri Luxe髓超嵌体为修复方法,观察组以Lava Ultimate髓超嵌体为修复方法。对两组修复效果、美观度及预后效果进行观察分析。结果:修复后12个月,观察组颌牙磨耗情况明显少于对照组(P<0.05);观察组红色美学指数(PES)评分、白色美学指数(WES)评分及咀嚼效率均高于对照组(P<0.05);观察组牙龈指数(GI)、龈沟出血指数(SBI)指标均低于对照组(P<0.05);观察组并发症发生率显著低于对照组(P<0.05)。结论:行根管治疗后磨牙缺损患者应用Lava Ultimate髓超嵌体进行修复有助于颌牙磨耗情况的减少,美观度及咀嚼能力明显提升,牙龈状况及并发症情况明显改善,远期治疗获益优势明显。

Ultimate两通接头技术在气质联用仪中的应用

文中论述了Ultimate两通接头技术在气质联用仪中的数种应用情况,针对气质联用仪分析时常见的放空周期长,色谱柱间切换步骤繁琐、分析复杂基质时色谱柱易污染易堵塞等问题,提出了用Ultimate两通接头技术进行解决的方法。

Lava Ultimate优韧瓷高嵌体修复无髓后牙牙体缺损的临床疗效

目的分析Lava Ultimate优韧瓷高嵌体修复无髓后牙牙体缺损的临床疗效。方法前瞻性选取2018年1月1日至2020年1月1日首都医科大学附属北京同仁医院诊治的无髓后牙牙体缺损患者62例。采用计算机随机数字分组法将其分成对照组和观察组,各31例。对照组患者接受Ceramage聚合瓷高嵌体修复,观察组患者接受Lava Ultimate优韧瓷高嵌体修复。比较两组患者临床疗效、咀嚼功能、牙龈反应及美观满意度。结果观察组患者临床总有效率为96.77%,高于对照组(77.42%),差异有统计学意义(P<0.05)。治疗前,两组患者咀嚼率比较,差异均无统计学意义(P>0.05);治疗6、12个月,观察组患者的咀嚼率为0.59±0.11、0.69±0.2,高于对照组(0.55±0.15、0.64±0.21),差异均有统计学意义(P<0.05)。治疗前,两组患者牙龈指数、菌斑指数比较,差异均无统计学意义(P>0.05);治疗后,观察组患者牙龈指数、菌斑指数为1.08±0.21、1.03±0.17,均低于对照组(1.95±0.26、1.89±0.25),差异均有统计学意义(P<0.05)。观察组患者美观总满意率为96.77%,高于对照组(70.97%),差异有统计学意义(P<0.05)。结论Lava Ultimate优韧瓷高嵌体修复无髓后牙牙体缺损能提升临床治疗效果,促使咀嚼功能恢复,优化牙龈健康情况,建议使用。

Lava Ultimate优韧瓷髓腔固位冠在大面积牙体缺损短冠磨牙修复中的应用观察

目的观察Lava Ultimate优韧瓷髓腔固位冠在大面积牙体缺损短冠磨牙修复中应用效果。方法大面积牙体缺损短冠磨牙85颗,分为Lava Ultimate优韧瓷髓腔固位冠组(优韧瓷组)40颗、氧化锆髓腔固位冠组(氧化锆组)45颗,分别采用Lava Ultimate优韧瓷、氧化锆髓腔固位冠修复。修复后12个月对两组髓腔固位冠修复体进行临床效果评价,包括修复体完整性、修复体松动及脱落、边缘适合性、边缘着色、继发龋和牙龈健康状况,计算临床成功率。修复后12个月进行满意度调查,包括修复体颜色、外形、咀嚼功能和舒适度4个方面。离体短冠恒磨牙20颗,制作Lava Ultimate优韧瓷以及氧化锆髓腔固位冠修复体各10个,分别记为LU组、ZrO2组,制作硅橡胶间隙印模后,观察修复体边缘适应性(M1点值)和内部适应性(M2、M3及M4点值)。结果优韧瓷组和氧化锆组的髓腔固位冠修复体边缘密合,无边缘着色及继发龋的发生。优韧瓷组在修复后12个月出现1例修复体咬合面破损、1例牙龈轻微炎症,临床成功率为95.0%;氧化锆组在修复后12个月时出现1例修复体脱落、2例牙龈轻微炎症,临床成功率为93.3%,两组临床成功率相比,P>0.05。优韧瓷组患者在修复体舒适度的满意率高于氧化锆组(P<0.05)。LU组M1、M2、M3、M4点间隙值均小于ZrO2组(P均<0.05)。结论与氧化锆相比,Lava Ultimate优韧瓷髓腔固位冠修复大面积牙体缺损短冠磨牙疗效相当,但患者舒适度更高,且Lava Ultimate优韧瓷髓腔固位冠修复体的边缘适应性和内部适应性均更优。

Effect of Strain Rate on Ultimate Strength and Fractograph in Tungsten Alloy

The effect of strain rate on ultimate strength and fractograph was investigated for tungsten alloy with four different technologies. As the strain rate rises, the ultimate strength increases and morphology of fracture surface gradually transits from detachment of interface between W pellets and matrices to cleavage of W pellets. Meanwhile, low strength tungsten alloy has higher sensitivity to strain rate.

A Computational Investigation of the Group Effect of Pits on the Ultimate Strength of Steel Plates

In this work, we focus on assessing the group effect of localized corrosion on the ultimate strength of the marine structural plates and study the load-deformation behaviors of plates of various slenderness and uniaxial compression.Meanwhile, we investigate different corroded patterns from a single circular pit to 25 circular pits distributed over the plate and carry out hundreds of nonlinear finite element simulations by combining the number, depth, distribution of pits with imperfections and slenderness of plate. The distribution of multiple pits causes scattering of stress concentration on the plate, then the plastic section of plate changes with wider distribution of damage simultaneously. The ultimate strength arises when un-loading zone comprised of the yielding strips and holes extends across the plate. It can be concluded that the corroded condition defined as group effect of pits manipulates the deformation state and the loading capacity of plate at the ultimate strength mode that coincides with the proportion of effective loading area and section in the process of post-buckling. To validate the effect of pits group, we perform the numerical experiments of the post-buckling of steel plates containing pits in a row with different orientation.

Ultimate Lateral Capacity of Rigid Pile in c–φ Soil

To date no analytical solution of the pile ultimate lateral capacity for the general c–φ soil has been obtained. In the present study, a new dimensionless embedded ratio was proposed and the analytical solutions of ultimate lateral capacity and rotation center of rigid pile in c–φ soils were obtained. The results showed that both the dimensionless ultimate lateral capacity and dimensionless rotation center were the univariate functions of the embedded ratio. Also,the ultimate lateral capacity in the c–φ soil was the combination of the ultimate lateral capacity（f;） in the clay, and the ultimate lateral capacity（f;） in the sand. Therefore, the Broms chart for clay, solution for clay（φ=0） put forward by Poulos and Davis, solution for sand（c=0） obtained by Petrasovits and Awad, and Kondner’s ultimate bending moment were all proven to be the special cases of the general solution in the present study. A comparison of the field and laboratory tests in 93 cases showed that the average ratios of the theoretical values to the experimental value ranged from 0.85 to 1.15. Also, the theoretical values displayed a good agreement with the test values.

Ultimately exposed roof area prediction of bauxite deposit goaf based on macro joint damage

The ultimately exposed roof area(UERA)of goaf is crucial to the safety and economics of underground mining.The prediction models do not consider the mechanical weakness of rock mass and ignore the influence of the joint damage factor,causing a large predicted exposure area with a high roof falling risk.This work adopted joint damage factor to derive a new UERA prediction model.The relationships between the UERA(S)and the span ratio(m),the density(k)and the diameter of fracture(d)were analysed by the new prediction model.The results showed that the exposed area S and the span ratio m have a U-shaped curve relationship.The S decreases with the increase of m and then increases when m is beyond 2.The exposed roof area S is in an inversely proportional power-law relationship with the fracture surface density k,and the curvature of the S-k relationship curve decreases when d=0.5 and k>7,and S is close to 0.There is a negative correlation between S and the fracture surface diameter d,the curvature of the S-d curve decreases with the increase of d and k,and the variation rate increases first and then decreases with the increase of d;when k=0.5 and d>9,S is close to 0.The predicted values of the UERA prediction model are 119.3,112.8,and 114.6 m2 with different joint damage parameters,which are slightly smaller than the actual critical exposure area of a roof(S=120 m2).The case study shows that the alternative prediction model is reasonable and acceptable and provides new theoretical support for the underground mining safety of sedimentary bauxite ore.

Impact of climate change on allowable bearing capacity on theQinghai-Tibetan Plateau

Climate change has a substantial impact on infrastructures in the permafrost on the Qinghai-Tibetan Plateau (QTP). In this study, the mean annual ground temperature (MAGT) and permafrost evolution were investigated in both the historical (1950-2005) and projected (2006-2099) periods. Then, an allowable bearing capacity model was used to discuss the allowable bearing capacity change on the QTP. Results show that the MAGT increased by 0.36 ℃ during 1950-2005. The MAGT will increase by 0.40 (RCP2.6), 0.79 (RCP4.5), 1.07 (RCP6.0), and 1.75 (RCP8.5)℃C during 2006-2099. In addition, the permafrost area has decreased by 0.195 × 10^6 km2 in 1950-2005. The permafrost area will decrease by 0.232 × 10^6 (RCP2.6), 0.468 × 10^6 (RCP4.5), 0.564 × 10^6 (RCP6.0), and 0.803 × 10^6 (RCP8.5) km2 during 2006-2099. With the degradation of permafrost, the allowable bearing capacity in permafrost zones would decrease accordingly. The decreasing trend is 6 kPa per 10 years in 1950-2005, and will be 0.6 (RCP2.6), 5 (RCP4.5), 7 (RCP6.0), and 11 (RCP8.5) kPa per 10 years during 2006-2099. The most remarkable trend would be observed under RCP8.5. Meanwhile, some scientific advices for the design, construction, operation and maintenance of permafrost engineering in the context of climate change were provided.

A deep-learning-based prediction method of the estimated ultimate recovery(EUR)of shale gas wells

The estimated ultimate recovery(EUR)of shale gas wells is influenced by many factors,and the accurate prediction still faces certain challenges.As an artificial intelligence algorithm,deep learning yields notable advantages in nonlinear regression.Therefore,it is feasible to predict the EUR of shale gas wells based on a deep-learning algorithm.In this paper,according to geological evaluation data,hydraulic fracturing data,production data and EUR evaluation results of 282 wells in the WY shale gas field,a deep-learning-based algorithm for EUR evaluation of shale gas wells was designed and realized.First,the existing EUR evaluation methods of shale gas wells and the deep feedforward neural network algorithm was systematically analyzed.Second,the technical process of a deep-learning-based algorithm for EUR prediction of shale gas wells was designed.Finally,by means of real data obtained from the WY shale gas field,several different cases were applied to testify the validity and accuracy of the proposed approach.The results show that the EUR prediction with high accuracy.In addition,the results are affected by the variety and number of input parameters,the network structure and hyperparameters.The proposed approach can be extended to other shale fields using the similar technic process.

Uniformly ultimate boundedness for discontinuous systems with time-delay

The uniformly ultimate boundedness of discontinuous systems with time-delay in the sense of Filippov solutions is discussed.Based on the Lyapunov-Krasovskii functional,the Lyapunov theorem for the globally strongly uniformly ultimate boundedness of retarded discontinuous systems is presented.Furthermore,the result is applied to a class of mechanical systems with a retarded discontinuous friction item.

Influence of the Spudcan Angle on the Ultimate Bearing Capacity of Jack-up Platform

Jack-up platforms of the Ocean engineering structures always withstand the vertical gravity loads which are applied to the seabed by spudcan, so it is important to determine the bearing capacity and the penetration depth of the spudcan for its geometry. In fact, it is up to the deformation law and the failure modes of soil surrounding the spudcan which can calculate the ultimate bearing capacity of the spudcan foundation on the soil seabed. By using the finite element analysis software Abaqus, the deformation law of soil around the spudcan is analyzed in detail, and the failure modes of soil surrounding the spudcan foundation are achieved. At the same time, based on the limit equilibrium theory, by use of static permissible slip-line field, the ultimate bearing capacity of the spudcan foundation is analyzed and the lower limit solution is derived theoretically, and the effect of the spudcan angle on the ultimate bearing capacity is investigated. The numerical results are compared with those obtained by the theoretical formulas deduced in this paper. On the basis of the lower limit solutions in this paper, the effect of the spudcan angle on the ultimate bearing capacity is revealed, and a practical bearing capacity formula is given to take the effect of the spudcan angle into consideration.