Stability analysis of loose accumulation slopes under rainfall:case study of a high‑speed railway in Southwest China

The high and steep slopes along a high-speed railway in the mountainous area of Southwest China are mostly composed of loose accumulations of debris with large internal pores and poor stability,which can easily induce adverse geological disasters under rainfall conditions.To ensure the smooth construction of the high-speed railway and the subsequent safe operation,it is necessary to master the stability evolution process of the loose accumulation slope under rainfall.This article simulates rainfall using the finite element analysis software’s hydromechanical coupling module.The slope stability under various rainfall situations is calculated and analysed based on the strength reduction method.To validate the simulation results,a field monitoring system is established to study the deformation characteristics of the slope under rainfall.The results show that rainfall duration is the key factor affecting slope stability.Given a constant amount of rainfall,the stability of the slope decreases with increasing duration of rainfall.Moreover,when the amount and duration of rainfall are constant,continuous rainfall has a greater impact on slope stability than intermittent rainfall.The setting of the field retaining structures has a significant role in improving slope stability.The field monitoring data show that the slope is in the initial deformation stage and has good stability,which verifies the rationality of the numerical simulation method.The research results can provide some references for understanding the influence of rainfall on the stability of loose accumulation slopes along high-speed railways and establishing a monitoring system.

基于Loose r-sample的网格质量保持技术

为保证虚拟手术系统中的网格质量,提出一种基于Loose r sample理论的快速表面网格重建算法。记录满足Loose r sample采样定理的点集,用以描述物体的轮廓。通过约束Delaunay方法对该点集进行三角化,标记顶点和Delaunay单元,重构新的网格。实验结果表明,该算法能够保证生成网格的质量,简化仿真复杂度。

Lock-loose托槽与传统托槽摩擦力特性的比较研究

目的在干燥和人工唾液环境中测量Lock-loose托槽结扎中间翼和结扎全翼时与弓丝之间滑动摩擦力和静摩擦力的大小,并与传统四翼托槽和自锁托槽进行对比。方法应用原子力显微镜观察不锈钢弓丝与不同托槽摩擦前后的表观形貌。选用Lock-loose托槽、传统四翼托槽和自锁托槽,分别与0.406 4 mm、0.457 2 mm不锈钢圆丝和0.457 2 mm×0.634 9 mm、0.482 6 mm×0.634 9 mm不锈钢方丝组合,其中Lock-loose托槽使用结扎中间翼和结扎全翼两种结扎方式。使用电子万能力学实验机测量干燥和人工唾液两种环境下弓丝在托槽内滑动的动、静摩擦力。结果不同尺寸弓丝与不同托槽摩擦前后的表面粗糙度无明显差异(P>0.05);Lock-loose托槽结扎中间翼与4种弓丝组合的动、静摩擦力均接近于0,与传统四翼托槽有明显差异(P<0.05);与0.457 2 mm×0.634 9 mm不锈钢方丝组合时,Lock-loose托槽结扎全翼可以获得最大动、静摩擦力,与传统四翼托槽和自锁托槽的差异有统计学意义(P<0.05);人工唾液环境中的摩擦力小于干燥环境中的摩擦力(P<0.05)。结论 Lock-loose托槽可以通过不同的结扎方式调节并获得临床所需的摩擦力,有效解决了低摩擦力与强支抗控制的矛盾问题。

集值映射的Loose Nash平衡点集的稳定性

本文讨论了集值映射的Ｌｏｏｓｅ Ｎａｓｈ平衡的稳定性，得到大多数（在Ｂａｉｒｅ分类的意义下）集值映射的Ｌｏｏｓｅ Ｎａｓｈ平衡点集是稳定的。

Strength performance of mortise and loose-tenon furniture joints under uniaxial bending moment

We determined the effects of adhesive type and loose tenon dimensions （length and thickness） on bending strength of T-shaped mor- tise and loose-tenon joints. Polyvinyl acetate （PVAc） and two-component polyurethane （PU） adhesives were used to construct joint specimens. The bending moment capacity of joints increased significantly with increased length and thickness of the loose tenon. Bending moment capacity of joints constructed with PU adhesive was approximately 13% higher than for joints constructed with PVAc adhesive. We developed a predictive equation as a function of adhesive type and loose tenon dimensions to estimate the strength of the joints constructed of oriental beech （Fagus orientalis L.） under uniaxial bending load.

Effects of loose deposits on debris flow processes in the Aizi Valley, southwest China

Loose deposits, rainfall and topography are three key factors that triggering debris flows.However, few studies have investigated the effects of loose deposits on the whole debris flow process.On June 28, 2012, a catastrophic debris flow occurred in the Aizi Valley, resulting in 40 deaths.The Aizi Valley is located in the Lower Jinsha River,southwestern Sichuan Province, China. The Aizi Valley debris flow has been selected as a case for addressing loose deposits effects on the whole debris flow process through remote sensing, field investigation and field experiments. Remote sensing interpretation and laboratory experiments were used to obtain the distribution and characteristics of the loose deposits, respectively. A field experiment was conducted to explore the mechanics of slope debris flows, and another field investigation was conducted to obtain the processes of debris flow formation, movement and amplification. The results showed that loose deposits preparation, slope debris flow initiation,gully debris flow confluence and valley debris flow amplification were dominated by the loose deposits.Antecedent droughts and earthquake activities may have increased the potential for loose soil sources in the Aizi Valley, which laid the foundation for debris flow formation. Slope debris flow initiated under rainfall, and the increase in the water content as well as the pore water pressure of the loose deposits were the key factors affecting slope failure. The nine gully debris flows converged in the valley, and the peak discharge was amplified 3.3 times due to a blockage and outburst caused by a large boulder. The results may help in predicting and assessing regional debris flows in dry-hot and seismic-prone areas based on loose deposits, especially considering large boulders.

Dynamics of loose granular flow and its subsequent deposition in a narrow mountainous river

A large amount of loose debris materials were deposited on the slope of mountainous areas after the 2008 Ms 8.0 Wenchuan earthquake. During and after the earthquake, these loose debris deposits collapsed and slide into valleys or rivers, changing river sediment supply condition and channel morphology. To investigate the mechanisms of granular flow and deposition, the dynamics of slope failure and sediment transportation in typical mountainous rivers of different intersection angles were analyzed with a coupling model of Computational Fluid Dynamics and Discrete Element Method(CFD-DEM). The numerical results show that the change of intersection angle between the granular flow flume and the river channel can affect the deposit geometry and the fluid flow field significantly. As the intersection angle increases, the granular velocity perpendicular to the river channel increases, while the granular velocity parallel to the river channel decreases gradually. Compared to the test of dry granular flow, the CFD-DEM coupling tests show much higher granular velocity and larger volume of sediments entrained in the river. Due to the river flow, particles located at the edge of the deposition will move downstream gradually and the main section of sediments deposition moves from the center to the edge of the river channel. As a result, sediment supply in the downstream river will distribute unevenly. Under the erosion of fluid flow, the proportion of fine particles increases, while the proportion of coarse particles decreases gradually in the sediment deposition. The build-up of accumulated sediment mass will cause a significant increase in water level in the river channel, thus creating serious flooding hazard in mountainous rivers.

Delayed presentation of a loose body in undisplaced paediatric talar neck fracture

Fractures of the talus are rare in children.A high index of suspicion is needed to avoid missing such an injury,which is not an uncommon occurrence especially with undisplaced fractures.We present an unusual case of an undisplaced talar neck fracture in a five-year-old child leading to a delayed presentation of a symptomatic osteochondral loose body in the ankle joint.To our knowledge there are no reports in the literature of osteochondral loose bodies occurring in conjunction with an associated undisplaced talar neck fracture in either children or adults.The loose body was removed using anterior ankle arthroscopy.The child had an uneventful post operative recovery and regained full range of movement and function of his ankle joint and was discharged at one year follow-up.We aim to highlight the need to have a low threshold to further evaluate symptomatic children after fracture healing of an undisplaced talar neck fracture for a possible associated loose bodyin the ankle joint.

Department of Civil Engineering, Universitas Katolik Parahyangan, Bandung, 40141, Indonesiaof loose sand with fungus

This article presents an innovative method of bio-mediated soil improvement for increasing the shear strength of loose sand.The improvement is realized by mixing the loose sand with the inoculum of Rhizopus oligosporus,a kind of fungus widely used in food industry for making Indonesian tempeh.The objective of this article is to investigate the performance and mechanism of mixing tempeh inoculum as a binding agent of loose sand particles.The inoculum dosage,water content of loose sand,and curing time were examined for identifying the increment of unconfined compressive strength(q_u)of the samples.The results showed that q_u of the treated samples increased when the inoculum dosage was elevated.It shows that 5.24%inoculum could yield 68 kPa of q_u,and 5%water content and 3 d curing time produced the maximum q_u.Moreover,the mechanism of hypha and mycelium in binding the soil particles was clearly observed using a digital microscope and scanning electron microscope.

SIMUUTION OF ELECTROMAGNETIC TUBE BULGING BASED ON LOOSE COUPLING METHOD

A loose coupling method is used to solve the electromagnetic tube bulging. ANSYS/ EMAG is used to model the time varying electromagnetic field with the discharge current used as excitation, in order to obtain the radial and axial magnetic pressure acting on the tube, the magnetic pressure is then used as boundary conditions to model the high velocity deformation of tube with DYNAFORM, The radial magnetic pressure on the tube decreases from the center to the tube end, axial magnetic pressure is greater near the location equal to the coil height and slight in the other region. The radial displacement of deformed workpicces is distributed uniformly near the tube center and decreases from the center to the end; Deformation from the location equal to coil height to the tube end is little. This distribution is consistent with the distribution of radial pressure; Effect of the axial magnetic pressure on deformation can be ignored, The calculated results show well agreements with the experimental results.

Finite element analysis of stress and strain distributions in mortise and loose tenon furniture joints

We studied the effect of loose tenon dimensions on stress and strain distributions in T-shaped mortise and loose tenon （M＆amp;LT） furni-ture joints under uniaxial bending loads, and determined the effects of loose tenon length （30, 45, 60, and 90 mm） and loose tenon thickness （6 and 8 mm） on bending moment capacity of M＆amp;LT joints constructed with polyvinyl acetate （PVAc） adhesive. Stress and strain distributions in joint elements were then estimated for each joint using ANSYS finite element （FE） software. The bending moment capacity of joints increased significantly with thickness and length of the tenon. Based on the FE analysis results, under uniaxial bending, the highest shear stress values were obtained in the middle parts of the tenon, while the highest shear elastic strain values were estimated in glue lines between the tenon sur-faces and walls of the mortise. Shear stress and shear elastic strain values in joint elements generally increased with tenon dimensions and corre-sponding bending moment capacities. There was consistency between predicted maximum shear stress values and failure modes of the joints.

X-ray tomography study on the structure of the granular random loose packing

Random loose packing is the minimum-density granular packing which can maintain mechanical stability. In this study, x-ray tomography is used to investigate the internal structure of an isotropically prepared random loose packing through a special apparatus to minimize the effect of gravity. It is found that the minimum packing density is around 0.587. The microscopic structural analysis of the packing is also carried out.

Hydraulic mechanism and time-dependent characteristics of loose gully deposits failure induced by rainfall

Failure of loose gully deposits under the effect of rainfall contributes to the potential risk of debris flow.In the past decades, researches on hydraulic mechanism and time-dependent characteristics of loosedeposits failure are frequently reported, however adequate measures for reducing debris flow are notavailable practically. In this context, a time-dependent model was established to determine the changesof water table of loose deposits using hydraulic and topographic theories. In addition, the variation inwater table with elapsed time was analyzed. The formulas for calculating hydrodynamic and hydrostaticpressures on each strip and block unit of deposit were proposed, and the slope stability and failure risk ofthe loose deposits were assessed based on the time-dependent hydraulic characteristics of establishedmodel. Finally, the failure mechanism of deposits based on infinite slope theory was illustrated, with anexample, to calculate sliding force, anti-sliding force and residual sliding force applied to each slice. Theresults indicate that failure of gully deposits under the effect of rainfall is the result of continuouslyincreasing hydraulic pressure and water table. The time-dependent characteristics of loose depositfailure are determined by the factors of hydraulic properties, drainage area of interest, rainfall pattern,rainfall duration and intensity.

Ground Subsidence in Areas of Loose Porous Aquifers

Groundwater is one of the important water resources in northern China's plain areas. Many severe geological hazards have occurred in these areas due to ground subsidence which is caused by over exploitation of groundwater. This paper introduces and analyses the ground subsidence caused by groundwater exploitation and its mechanism in the northern China's plains. A ground subsidence prediction model has been developed based on the consolidation theory. The authors have tested this model in a case study of Fuyang City, Anhui Province, where ground subsidence is a severe environmental problem. In the case study, the model results match very well with those of the actual measurement. Two schemes of groundwater exploitation are assessed. The conclusion from the study could be used in the long-term water and economical management planning. The strategies for the control of ground subsidence are discussed.

Eff ect of Cementation on Calcium Carbonate Precipitation of Loose Sand Resulting from Microbial Treatment

Microbe-induced calcite precipitation is a sustainable improvement technique for sandy soil, which can alter the properties of sand via microbial activity. In this study, we investigated the loose-sand-consolidation eff ect by controlling the injection velocity, bacterial and cementingsolution concentrations, and hold times. The results demonstrate that, as the cyclic batch increases, the utilization rate of the bacterial fl uid increases and both the optical density(OD_(600)) of the bacteria and urease activity decrease. Moreover, it was determined that a 3-h hold time for a 0.5 mol/L cementing solution with a cementing fl uid velocity of 2 mL/min has the greatest bonding eff ect. The fi nal strength of the loose sand with an increase in calcium carbonate content was further discussed.

Prediction of oxygen concentration and temperature distribution in loose coal based on BP neural network

An effective method for preventing spontaneous combustion of coal stockpiles on the ground is to control the air-flow in loose coal.In order to determine and predict accurately oxygen concentrations and temperatures within coal stockpiles,it is vital to obtain information of self-heating conditions and tendencies of spontaneous coal combustion.For laboratory conditions,we designed our own experimental equipment composed of a control-heating system,a coal column and an oxygen concentration and temperature monitoring system,for simulation of spontaneous combustion of block coal(13-25 mm) covered with fine coal(0-3 mm).A BP artificial neural network(ANN) with 150 training samples was gradually established over the course of our experiment.Heating time,relative position of measuring points,the ratio of fine coal thickness,artificial density,voidage and activation energy were selected as input variables and oxygen concentration and temperature of coal column as output variables.Then our trained network was applied to predict the trend on the untried experimental data.The results show that the oxygen concentration in the coal column could be reduced below the minimum still able to induce spontaneous combustion of coal — 6% by covering the coal pile with fine coal,which would meet the requirement to prevent spontaneous combustion of coal stockpiles.Based on the prediction of this ANN,the average errors of oxygen concentration and temperature were respectively 0.5% and 7 °C,which meet actual tolerances.The implementation of the method would provide a practical guide in understanding the course of self-heating and spontaneous combustion of coal stockpiles.

Estimation of Loose Status of Jigging Bed Based on Adaptive Neuro-Fuzzy Inference System

In the separation process with a jig washer, an accurate on-line measurement of loose status of a jigging bed is essential for a successful control of coal quality and loose status is difficult to measure on-line directly in industrial process situations. So a soft-sensor technology is needed for this purpose. The soft-sensor model is developed in the experiment by an adaptive neuro-fuzzy inference system (ANFIS) which has a remarkable ability of learning and generalization. Based on the analysis of the technologic mechanism of jigging bed, the structure of the ANFIS is established to build the soft-sensor model of loose status estimation. The ANFIS is trained by a hybrid learning algorithm. Finally, the simulation results and comparison analysis are presented, which indicate that the ANFIS has better abilities of learning and generalization than the RBF and the BP networks. Thus, it is possible that the loose status of the jigging bed can be estimated on-line by using ANFIS.

Fractal analysis of thermal conduction of loose coal

For deep mining engineering, heat transfer of coal mass is a vital factor in the thermal environment of coal mines. In order to study the thermal conduction mechanism, we obtained gray images of coal mass microstructure by scanning samples with a digital microscope. With the use of Matlab, these gray images were transformed into binary images, which were then transformed into a corresponding matrix consisting only of the values 0 and 1. According to the calculation method of box-counting dimension, we calculated the fractal dimension of the loose coal to be approximately 1.86. The thermal conductivity expressions of loose coal were derived based on the simulation method of thermal resistance. We calculated the thermal conductivity of loose coal by using a fractal model and compared the calculated values with our experimental data. The results show that the test data show an encourag-ing agreement with the calculated values. Hence fractal theory is a feasible method for studying thermal conductivity of loose coal.

Wave Hindcast for the Neighbouring Seas of Korea Based on Loosely Coupled Wave-Tide-Surge Model

A hindcast simulation of 75 typhoons and winter monsoons which affected the coastal areas of Korean Peninsula is performed by use of a third generation ocean wave prediction model, WAM-cycle 4 model, loosely coupled with a com-bined tide and surge model. Typhoon wind fields are derived from the planetary marine boundary layer model for effective neutral winds embedding the vortical storm wind from the parameterized Rankin vortex type model in the limited areas of the overall modeled region. The hindcasted results illustrate that significant wave heights (SWH) considering the wave-tide-surge coupled process are significantly different from the results via the decoupled case especially in the region of the estuaries of the Changjiang Estuary, The Hangzhou Bay, and the southwestern tip of Korean Peninsula. This extensive model simulation is the first attempt to investigate the strong wave-tide-surge interaction for the shallow depth area along the coasts of the Yellow Sea and the East China Sea Continental shelf.

Giant Loose Body of Knee Joint Presenting as Accessory Patella<br/>—A Case Report

Loose bodies are freely floating fragments of cartilage or bone inside the knee joint space. This is commonly seen in association with degenerative joint disease (DJD), direct or indirect trauma, synovial chondromatosis, osteochondritis dissecans (OCD) and size of the loose body may vary from few millimeters to few centimeters. Patients with loose bodies in knee joint presented to orthopaedists with knee pain, swelling and restricted movement, with intermittent locking or catching of the joint. This is managed surgically most of the times when it becomes symptomatic. The surgical technique most commonly utilized is arthroscopy. Open arthrotomy should be done when the loose bodies are very large/numerous/located in posterior joint space. In review of literature, we found very few cases of giant loose body in knee joint due to DJD reported in last 70 years. We are hereby reporting our case of 60-year-old male with a giant loose body of same size as of patella in the supra-patellar pouch of left knee joint and managed by arthrotomy to remove the giant loose body. Post-operatively patient recovered significantly over the period of 6-week follow-up. In conclusion, giant loose body should be removed through arthrotomy and all such cases should be thoroughly evaluated to diagnose the cause of giant loose body.