Deformation warning index for reinforced concrete dam based on structural health monitoring data and numerical simulation

The material mechanical parameters of the dam body and foundation will change when a dam is reinforced during the aging process.This causes significant changes in the structural state of the project and makes it difficult to ensure its structural safety.In this study,a new deformation warning index for reinforced concrete dams was developed according to the prototype monitoring data,statistical models,three-dimensional finite element model(FEM)numerical simulation,and the critical conditions of the dam structure.A statistical model was established to separate the water pressure component.Then,a three-dimensional FEM of the reinforced concrete dam was constructed to simulate the water pressure component.Furthermore,the deformation components that affected the mechanical parameters of the dam under the same amount of reservoir water level change were separated and quantified accurately.In addition,the method for inversion of comprehensive mechanical parameters after dam reinforcement was used.The influence mechanisms of the deformation behavior of concrete dams under the reservoir water level and temperature changes were investigated.A new deformation warning index was developed by combining the forward-simulated critical water pressure component and temperature component in the period of extreme temperature decrease with the aging component separated by the statistical model.The new deformation warning index considers the structural state of the dam before and after reinforcement and links the structural strength criterion and the deformation evolution mechanisms.It provides a theoretical foundation and decision support for long-term service and operation management of reinforced dams.

Relationship between glutathione and malonaldehyde levels in erythrocytes and the deformation index of erythrocyte in patients at various periods following acute cerebral infarction

BACKGROUND： Glutathione, as an in vivo free radical scavenger, plays an important role in the anti-oxidation defense mechanism in patients with acute cerebral infarction. OBJECTIVE： To observe the relationship between the levels of glutathione （GSH） and malonaldehyde （MDA）, the metabolite of lipid peroxidation, in erythrocyte and deformation index of erythrocyte in patients at various periods following acute cerebral infarction. DESIGN： Controlled observation.SETTING： Qilu Hospital of Shandong University and Institute of Cerebrovascular Disease of Qingdao Medical College. PARTICIPANTS： We chose 98 inpatients with acute cerebral infarction from Department of Neurology, Qilu Hospital of Shandong University from January to December 2000 , serving as cerebral infarction group, including 50 male and 48 female, with mean age of （62±7）years. There were 23 cases found on the 1^st day after onset; 25 cases on the 3^rd day after onset; 25 cases on the 7^th day after onset; 25 cases on the 14th days after onset, and they were all confirmed by craniocerebral CT or MRI. Another 30 homeochronous inpatients with neurosis, cervical syndrome, lumbar intervertebral disc herniation and motor neuron disease were chosen as control group, including 20 male and 10 female, with mean age of （52±8）years . There was no significant difference in age and gender distribution between two groups （P 〉 0.05）. Patients in the two groups were informed of detected index.METHODS：①Ulnar venous blood was chosen from the patients who were fasted on the 1^st, 3^rd,7^th and 14^th days after onset. Deformation index of erythrocyte was measured with BL88-CKX laser diffraction erythrocyte deformeter and photographing was performed. GSH level in erythrocyte was measured with DTNB assay introduced by Beu-tler. MDA level in erythrocyte was measured with modified thiobarbituric acid colorimetric method.②At each sample collecting , according to the criteria accepted by the Fourth National Conference of Cerebrovascular Disease, intergrant of neurologic impairment 〈 15 points was regarded as mild （n=46）, 15 to 30 points as moderate （n=40）and, 〉 30 points as severe （n=12）. ③ t test was used to compare data between two groups , and linear correlation analysis was used in relationship analysis among indexes. MAIN OUTCOME MEASURES ：① Comparison of erythrocyte GSH and MDA levels and deformation index of erythrocyte at various periods between patients with acute cerebral infarction and controls. ②Correlation of erythrocyte GSH level with erythrocyte MDA level and with deformation index of erythrocyte in patients with cerebral infarction . ③ Relationship between erythrocyte GSH level and severity of disease in patients with acute cerebral infarction. RESULTS： Totally 98 patients with acute cerebral infarction and 30 controls all entered the stage of result analysis. ① Erythrocyte GSH level and deformation index of erythrocyte were lower on the 1^st, 3^rd, 7^th and 14^th days after onset in cerebral infarction group than in control group （P 〈 0.05-0.01）, and erythrocyte MDA level was significantly higher in cerebral infarction group than in control group （P 〈 0.05-0.01）. The three indexes changed most significantly on day 3 after onset in patients, and began to recover or decrease on day 7 after onset and inclined to be normal on day 14 after onset. ② Erythrocyte GSH level was significantly negatively correlated with erythrocyte MDA level in patients with acute cerebral infarction on the 1^st, 3^rd, 7^th and 14^th days after onset （r=-0.534, -0.713, -0.645, -0.656, respectively, P 〈 0.05-0.01 ） ,and significantly positively correlated with erythrocyte deformation index （t-=0.502, 0.560, 0.455, 0.504, respectively, P 〈 0.05）. ③Erythrocyte GSH level was significantly lower in moderate or severe patients with acute cerebral infarction than in mild patients[（0.215±0.088）,（0.192±0.102）, （0.281±0.090） g/L, P〈 0.05]. CONCLUSION：①Erythrocyte GSH and MDA levels and deformation index of erythrocyte change significantly on the 3^rd day following acute cerebral infarction. Index detection results gradually tended to be normal on from the 7^th day to 14^th days day after onset. ② Change of erythrocyte GSH level can reflect the severity of disease of patients with acute cerebral infarction.③Decrease of erythrocyte GSH level in patients with acute cerebral infarction is one of reasons that result in the decrease of deformation ability of erythrocyte.

A new estimation method and an anisotropy index for the deformation modulus of jointed rock masses

The deformation modulus of a rock mass is an important parameter to describe its mechanical behavior.In this study,an analytical method is developed to determine the deformation modulus of jointed rock masses,which considers the mechanical properties of intact rocks and joints based on the superposition principle.Due to incorporating the variations in the orientations and sizes of joint sets,the proposed method is applicable to the rock mass with persistent and parallel joints as well as that with nonpersistent and nonparallel joints.In addition,an anisotropy index AIdmfor the deformation modulus is defined to quantitatively describe the anisotropy of rock masses.The range of AIdmis from 0 to 1,and the more anisotropic the rock mass is,the larger the value of AIdmwill be.To evaluate the proposed method,20 groups of numerical experiments are conducted with the universal distinct element code(UDEC).For each experimental group,the deformation modulus in 24 directions are obtained by UDEC(numerical value)and the proposed method(predicted value),and then the mean error rates are calculated.Note that the mean error rate is the mean value of the error rates of the deformation modulus in 24 directions,where for each direction,the error rate is equal to the ratio of numerical value minus predicted value to the numerical value.The results show that(i)for different experimental groups,the mean error rates vary between 5.06%and 22.03%;(ii)the error rates for the discrete fracture networks(DFNs)with two sets of joints are at the same level as those with one set of joints;and(iii)therefore,the proposed method for estimating the deformation modulus of jointed rock masses is valid.

Novel association between sperm deformity index and oxidative stress-induced DNA damage in infertile male patients

Aim:To investigate the impact of abnormal sperm morphology using the sperm deformity index (SDI) on reactive oxygen species (ROS) production and its correlation with sperm DNA damage.Methods:Semen samples were collected from men undergoing infertility screening (n=7) and healthy donors (n=6).Mature spermatozoa were isolated and incubated with 5 mmol/L β-nicotinamide adenine dinucleotide phosphate (NADPH) for up to 24 h to induce ROS.Sperm morphology was evaluated using strict Tygerberg's criteria and the SDI.ROS levels and DNA damage were assessed using chemiluminescence and terminal deoxynucleotidyl transferase-mediated fluorescein- dUTP nick end labeling (TUNEL) assays,respectively.Results:SDI values (median [interquartiles]) were higher in patients than donors (2 [1.8,2.1] vs.1.53 [1.52,1.58],P=0.008).Aliquots treated with NADPH showed higher ROS levels (1.22 [0.30,1.87] vs.0.39 [0.10,0.57],P=0.03) and higher incidence of DNA damage than those not treated (10 [4.69,24.85] vs.3.85 [2.58,5.10],P=0.008).Higher DNA damage was also seen following 24 h of incubation in patients compared to donors.SDI correlated with the percentage increase in sperm DNA damage following incubation for 24 h in samples treated with NADPH (r=0.7,P=0.008) and controls (r=0.58,P=0.04). Conclusion:SDI may be a useful tool in identifying potential infertile males with abnormal prevalence of oxidative stress (OS)-induced DNA damage.NADPH plays a role in ROS-mediated sperm DNA damage,which appears to be more evident in infertile patients with semen samples containing a high incidence of morphologically abnormal spermatozoa.

A comparative assessment of rock mass deformation modulus

Deformation modulus of a rock mass(E_m) is one of the most important design parameters in construction of rock engineering projects such as underground excavations.However,difficulties are frequently encountered during in-situ tests which are also time-consuming and expensive for determining this parameter.Although E_m is often estimated indirectly from proposed equations by different researchers,many of these equations cannot be used in case of problematic rock conditions(thinly bedded,highly jointed rock masses,etc.) as high quality core samples are required.This study aims to explore more practical and useful equation for E_m estimation using Rock Quality Designation(RQD) and point load index values.Comparisons were made between available empirical equations and the proposed E_m equation in terms of the estimation capacity.Multiple comparison tests(ANOVA) showed that E_m can be reliably estimated using proposed equation especially at the preliminary stages of projects.

Granite deformation and behavior of acoustic emission sequence under the temperature and pressure condition at different crust depths

Results of triaxial compression experiment results show that granite rock strength increases with the depth until 30 km. In shallow crust, rock failure exhibits abrupt or quasi-abrupt instability under lower pressure. Acoustic Emission (AE for short) distributed almost uniformly before and after failure. Go through downwards into the depth range with progressive failure feature, there are no or only a few number of AE before and after failure. In deeper range, rock failure shows some feature of quasi-abrupt instability under high pressure. There are still few AE before failure, but with the stick-slip, much more An events were detected after failure. Under the temperature and pressure condition of more deep crust (about 26 km), rock failure takes abrupt instability under high pressure as main feature, there are dense AE activities before failure and cumulated frequency of AE increases exponentially before the failure. In about 35 km depth range, rock strength decreases quickly with the depth and sample exhibits semi-ductile or ductile progressive fails, there are no AE being detected before and after failure. The b value of AE sequence before failure seems a little smaller than that after failure, and b value roughly decreased with depth. The numerical range of index α is the widest in about 18 km depth and becomes narrow in the condition of more shallow or more deep crust. So, when the temperature and pressure condition simulating the real environment of focal depth changes from shallow to deep in the crust, the range of a of microfracture sequence would undergo such an evolvement process that a changes from narrow to wide and then to narrow again.

基于地表敏感变形和房屋因素的矿区建筑物损坏评价方法

针对目前建筑物采动损坏评价因素的不尽合理与区域性评判结果的局限性,提出基于地表敏感变形和房屋因素的矿区建筑物采动损坏评价方法。采用理论分析、数值模拟和现场调查等方法对建筑物采动损坏评价进行了研究与探讨。首先,采用数值模拟方法,揭示地表变形、建筑物结构类型、主变形方向与建筑物长轴的夹角等因素对建筑物损坏影响规律,模拟结果表明:①当沿建筑物长轴的变形增大时,建筑物的损坏程度增大,得出了平房建筑加速损伤的地表变形临界值为曲率K=0.6 mm/m^(2),水平变形ε=6 mm/m;②不同结构的建筑物损坏程度不同,其中具有圈梁或构造柱的建筑物抗变形能力强,研究并确定了二层砖混结构(圈梁和构造柱)损坏程度的地表临界变形值;③建筑物对其长轴方向的地表变形较为敏感,影响损坏大,但对其长轴的垂直方向的变形不太敏感,而变形与建筑物斜交方向的建筑物损坏程度介于2者之间。其次,基于地表敏感变形因素、主变形方向、房屋因素共选取7个评价指标,建立建筑物采动损坏评价的未确知测度模型,根据各评价指标对建筑物的重要程度,采用层次分析法定权;最后,应用于峰峰矿区和徐州矿区3个村庄的建筑物损坏实例,结果表明:在选取的50户140余栋建筑物评价中,预测准确率在80%以上,预测精度高于传统方法,且预测效果良好,弥补了传统评价方法的不足,验证了评价指标选取和评价模型的可靠性。

大排列微地震实时监测技术在页岩油水力压裂中的应用

页岩油是重要的国家战略资源。在中国,以陆相页岩油为主,特别是济阳凹陷,页岩储层地质条件复杂,常用的裂缝识别技术包括蚂蚁体、相干体和曲率体等,无法满足精度要求,开采面临巨大挑战。为了加快页岩油的开发,在樊页1井组页岩油示范区开展基于大排列微地震实时监测,通过闭环优化过程进行施工参数迭代和技术方案优化。根据微地震震源参数,提出了计算储层改造体积和裂缝复杂性指数的新方法,用于定量评估储层改造波及范围和裂缝的复杂性。文中主要描述了在樊页1井组页岩油示范区开展的基于大排列微地震实时监测技术的地质工程一体化实践,所取得的认识和经验具有一定的借鉴价值。

基于面板数据模型的拱坝缺失数据填补方法

混凝土拱坝作为重要的水工建筑物,由于监测设备故障、人为因素等影响,导致其监测数据频繁出现缺失的现象,降低了大坝安全评估与预测的有效性与准确性。传统方法多仅依赖单测点测值进行插补,忽略了测点之间的相关性与异质性。本文提出了一种基于面板数据模型的变形缺失数据插补方法。首先,改进传统变形相似性增量速度指标,解决了其分母可能等于零的问题。其次,提出了一种组合加权方法以计算变形相似性综合指标,并采用改进的基于密度聚类方法对变形监测点进行分类。随后,建立了面板模型,以填补不同区域内的缺失数据。本文提出的方法可以更准确地填补混凝土拱坝变形数据的缺失,从而能够有效地解决变形监测数据缺失的问题。

超高沥青混凝土心墙坝砂板岩堆石料试验研究

开展了超高沥青混凝土心墙坝砂板岩堆石混合料的试验研究。研究结果表明:随板岩含量的提升和孔隙率的增大,应力应变曲线软化特性趋弱硬化特性增强、剪切峰值降低,剪切过程中的体变增大且剪胀现象减弱,相应的线性强度c,φ和非线性强度指标φ_(0),Δφ均降低,邓肯模型参数K与Kb减小;建立了同时可反映孔隙率、板岩含量的强度指标及邓肯模型参数经验公式,能较高精度地预测不同板岩含量、不同孔隙率砂板岩堆石混合料的工程力学特性;板岩含量是影响渗透性能的重要因素,随板岩含量的提升渗透系数降低,工程建设中对于含板岩的堆石料应关注排水设计。

鄱阳湖地区级配不良偏细砂砾石料力学特性

基于大型三轴试验数据,研究了级配和相对密度D_(r)对鄱阳湖地区级配不良偏细砂砾石料强度和变形特性的影响。结果表明:随着小于5 mm粒径颗粒质量分数的增加,砂砾石料压实性能降低;随着大于5 mm粒径颗粒质量分数P_(5)和D_(r)的增大,强度指标、初始切线弹性模量与体积模量增大;本文研究范围内,随P_(5)和D_(r)的增大,强度指标c、φ、φ_(0)、Δφ线性增大,且P^(5)和D_(r)对强度指标的作用效应几乎不存在相互影响;随P 5和D_(r)的增大,邓肯E-B模型参数K、K_(b)增大,且P_(5)越高D_(r)对K、K_(b)的影响越显著,D_(r)越大时P_(5)对K、K_(b)的影响越强烈,存在相互影响效应;提出了考虑级配与D_(r)双重影响的强度指标和变形参数经验计算公式,该公式能高精度预测鄱阳湖地区级配不良偏细砂砾石覆盖层料的力学指标。

振动轮两侧加速度差异及连续压实指标优化研究

连续压实控制技术主要通过振动轮单侧振动响应描述土体压实状态,已在工程中得到广泛应用。然而,研究发现压实过程中存在振动轮两侧加速度响应不一致的现象,这可能导致现有测试方法在相同位置出现不同的刚度测试结果,因此研究振动轮两侧振动差异性对提高连续压实测试精度具有重要意义。结合现场试验,采集压路机振动轮两侧的加速度信号,重点分析了不同压实遍数、振动频率下两侧加速度峰值、倍频幅值的变化与分布规律;以双侧响应为基础提出平均指标,通过相关性分析对指标适用性进行验证。研究结果表明:随着压实遍数的增加,两侧加速度峰值差异逐渐减小,经4遍压实后差异由24.4%降至13.3%;振动轮结构偏心会造成振动轮两侧加速度频谱中基频幅值差异的产生,被压土体两侧刚度不均会造成2倍频、3倍频幅值差异的产生;双侧平均指标μAICV与动态变形模量的相关性为0.75,表明双侧平均指标μAICV可用于路基压实质量控制,相比单侧连续压实控制指标,可有效提高现场质量控制精度。

考虑防洪风险的混凝土坝变形双控指标拟定方法研究

针对基于典型小概率法拟定大坝监控指标时的失效概率取值偏经验性以及目前变形监控指标未考虑变形变化速率的问题,将大坝变形失效风险与大坝防洪风险(上游来水和泄洪能力)相结合,将失效概率取设计防洪风险,采用典型小概率法拟定了关键测点变形监控指标,再基于设计洪水调洪演算库水位及其对应的变形分量变化速率,从而确定变形速率监控指标,提出了考虑防洪风险的混凝土坝变形和变形速率双监控指标的拟定方法。以某服役期高拱坝为例,拟定了典型测点实测变形和变形速率双监控指标,实测变形数据及其变化速率均小于拟定的变形监控指标和变形速率监控指标,这表明该大坝当前变形性态安全可控。

建立骨质疏松性椎体压缩骨折术后再骨折预测模型

目的探讨骨质疏松性椎体压缩骨折(osteoporotic vertebral compression fracture,OVCF)术后再骨折风险,构建风险预测模型,确定有效防治措施。方法选取2021年8月至2022年6月北京积水潭医院收治的119例OVCF患者作为研究对象,根据术后再骨折与否分为再发组和非再发组,其中再发组22例,男11例,女11例;年龄55~86岁,平均(72.02±5.58)岁。非再发组97例,男50例,女47例;年龄55~86岁,平均(70.79±6.81)岁。统计两组一般资料,采用Lasso-Logistic回归模型筛选OVCF术后再发骨折自变量,采用赤池信息准则(Akaike’s information criterion,AIC)、贝叶斯信息准则(Bayesian information criterion,BIC)比较全变量Logistic回归、逐步Logistic、Lasso-Logistic回归预测效能,构建诺莫图模型,采用受试者工作特征曲线(receiver operating characteristic,ROC)、校准曲线分析OVCF术后再发骨折诺莫图模型效能。结果术后随访8~20个月,平均(12.00±2.40)个月。单因素分析显示,再发组身体质量指数(body mass index,BMI)、骨密度T值、抗酒石酸酸性磷酸酶(tartrate-resistant acid phosphatase 5b,TPACP-5b)、核因子kB受体激活因子配体(receptor acti-vator nuclear factor kappa B ligand,RANKL)、骨保护素(osteoprotegrin,OPG)、术后抗骨质疏松治疗、白细胞介素(interleukin,IL)-17、长期糖皮质激素使用史、脊柱畸形指数(spinal deformity index,SDI)值、手术段Cobb角、后凸角度与非再发组比较,差异有统计学意义(P<0.05);Lasso-Logistic回归模型分析显示lambda.lse值0.049为最优模型,此时进入模型的变量涉及骨密度、SDI值、IL-17、术后抗骨质疏松治疗,经BIC、AIC验证表明所构建模型拟合和预测效果相对较好;诺莫图模型的ROC下面积(area under the curve,AUC)为0.865,敏感度及特异度分别为95.45%、68.04%,且校准曲线显示,其预测效能与实际吻合较好。结论OVCF术后再骨折的发生受围手术期多方面影响,涉及骨密度T值、SDI值、IL-17、术后抗骨质疏松治疗,基于以上因素可有效预测患者再骨折风险,为临床防治再骨折提供参考依据。

基于液化砂土地基等能量等变形挤密群桩现场试验规律分析

为解决地震导致地基饱和砂土和粉土液化,造成建筑沉降、倾斜甚至破坏的发生,以海南省海口市江东新区房建项目砂性地基土严重液化为依托,采用等能量等变形挤密桩技术进行桩周土的二次挤密加固,通过加固前后标准贯入度试验击数计算液化指数(I_(LE)),再进行单桩竖向抗压静载试验检验承载力。现场试验得出,处理深度内整体地基土由原严重液化程度改善为轻微液化趋近于不液化;前后标贯随深度平均锤击数之差拟合方程为Y=0.307857X+10.3617,R^(2)=0.84792,Pearson系数为0.93109,前后标贯平均击数在-5 m至-13 m区间内每层提高12~15击,各土层加固均匀;加固后地基达到单桩承载力设计特征值2250 kN。研究规律可供类似工程提供参考。

自锁托槽矫治器联合口腔正畸在牙颌畸形患者的应用效果评价

目的评价自锁托槽矫治器联合口腔正畸在牙颌畸形患者的应用效果。方法回顾性分析我院2020年1月~2023年1月进行口腔正畸的牙颌畸形患者102例,按治疗方法分为金属托槽组(n=51)和自锁托槽组(n=51)。金属托槽组采用金属托槽矫治器治疗,自锁托槽组采用自锁托槽矫治器治疗。对比2组治疗效果、治疗前后牙周指数[牙龈指数(gingival index,GI)、龈沟出血指数(Gingival sulcus bleeding index,SBI)]、龈沟液生化指标[谷草转氨酶(aspartate transaminase,AST)、碱性磷酸酶(alkaline phosphatase,ALP)]水平。结果自锁托槽组总有效率96.08%(49/51)较金属托槽组76.47%(39/51)高(P<0.05);治疗后与金属托槽组比较,自锁托槽组TNF-α、IL-1β低(P<0.05);治疗后与金属托槽组比较,自锁托槽组GI、SBI低(P<0.05);治疗后与金属托槽组比较,自锁托槽组AST、ALP低(P<0.05)。结论自锁托槽矫治器联合口腔正畸在牙颌畸形患者中的应用效果显著,能减轻龈沟液炎症,降低相关生化指标水平,改善患者牙周指数。

考虑基坑宽度及软弱土层厚度的基坑抗隆起稳定可靠度研究

坑底隆起破坏是导致基坑失稳的关键因素之一。对坑底隆起的影响因素展开研究工作,分析基坑宽度以及软弱土层厚度对坑底隆起变形以及基坑抗隆起稳定可靠度的影响规律。首先,建立不同工况的基坑开挖有限元模型,获取坑底不同特征点的隆起变形值,分析其变形规律,进而构建基于隆起变形限值的坑底抗隆起失效极限状态函数,最后采用蒙特卡罗法对坑底进行概率分析。数值模拟结果表明:当软弱土层厚度足以使隆起破坏滑动面贯通时,窄基坑的坑底两侧隆起变形大,中间小,宽基坑隆起变形规律与之相反;两种类型基坑坑底隆起变形都随基坑宽度增加而增大。改变软弱土层厚度,坑底各特征点隆起变形值随之变化,当为窄基坑时,坑底隆起变形依旧是中间小,两侧大;当基坑为宽基坑时,随软弱土层厚度增加,隆起变形随之增大,且坑底中心隆起变形逐渐超过两侧隆起变形;依据变形规律得到不同宽度基坑隆起破坏滑动面贯通时的软弱土层厚度。坑底抗隆起稳定可靠度与基坑宽度、特征点位置以及软弱土层厚度有关,坑底的稳定状态以及可靠度最低的特征点位置随基坑宽度以及软弱土层厚度变化而变化。

复杂环境下深大基坑施工变形监测与分析

针对填海造陆建设用地淤泥与砂土层深基坑施工中的变形与稳定性问题,以地表沉降变形不大于36 mm、管线沉降不大于28 mm、锚桩支护结构顶部最大水平位移不大于6 mm作为基坑开挖稳定的评价指标。以深圳机场某站前综合配套保障用房项目基坑支护工程为例,介绍了超深基坑监测布置方案,并基于监测数据研究了深大基坑的周边道路及管线的沉降、地下水位升降、围护结构水平及竖向变形规律,研究结果表明基坑开挖引起的道路及管线的沉降、围护结构水平及竖向变形均处于预警范围内,基坑开挖过程中的稳定性较好。

合肥弱膨胀土力学特征及饱水扰动影响

为了研究合肥地区弱膨胀土遇水及扰动对其强度和变形等力学性质的影响,对合肥地铁7号线徽富路站深基坑内弱膨胀土的原状样及饱和扰动样,分别开展了50 kPa,100 kPa和200 kPa三种围压下常规饱和三轴压缩(CTC)和三轴拉伸(CTE)以及原状非浸水样双压力室三轴压缩试验。通过对比原状样与饱和扰动样的应力–应变、强度指标以及变形模量的差异,探讨了饱水扰动对膨胀土力学性质的影响,且采用XRD衍射测试了膨胀土的矿物成分及含量。试验结果表明:(1)合肥地铁7号线基坑土质为弱膨胀土,黏土矿物中蒙脱石含量占46%;(2)合肥地铁7号线基坑的弱膨胀土强度的降低主要表现为黏聚力的降低,原状样较扰动饱和重塑样黏聚力下降了56%,而内摩擦角的变化并不显著;(3)合肥地铁7号线基坑内弱膨胀土有超固结现象,表现为原状样具有剪胀软化特征;(4)合肥地铁7号线基坑弱膨胀土原状样遇水扰动后初始模量下降了20%左右,水的浸润大幅降低了膨胀土抗变形能力。

钢板夹心混凝土组合剪力墙的变形能力研究

为研究钢板夹心混凝土组合剪力墙的变形能力,该文基于平截面假定推导了钢板夹心混凝土组合剪力墙的截面曲率延性系数,并利用等效塑性铰假定进一步得到其位移延性系数,通过已有试验结果验证了该计算方法的可靠性。利用该计算方法研究了轴压比、端柱套箍指标、剪力墙高宽比、钢板强度、混凝土强度等参数对钢板夹心混凝土组合剪力墙位移延性系数的影响。研究表明:通过控制剪力墙轴压比,适当提高端柱套箍指标,使用低强度钢材以及设置有效构造隔板可有效保证剪力墙的变形能力。