Seismic response of precast reinforced concrete wall subjected to cyclic in-plane and constant out-of-plane loading

This paper provides insight into the seismic behavior of a full-scale precast reinforced concrete wall under in-plane cyclic loading combined with out-of-plane loading replicated by sand backfill to simulate the actual condition of basement walls. The tested wall exhibited flexural cracks, owing to the high aspect ratio and considerable out-of-plane movement due to lateral pressure from the backfill. The wall performed satisfactorily by exhibiting competent seismic parameters and deformation characteristics governed by its ductile response in the nonlinear phase during the test with smaller residual drift. Numerical analysis was conducted to validate experimental findings, which complied with each other. The numerical model was used to conduct parametric studies to study the effect of backfill density and aspect ratio on seismic response of the proposed precast wall system. The in-plane capacity of walls reduced, while deformation characteristics were unaffected by the increase in backfill density. An increase in aspect ratio leads to a reduction in in-plane capacity and an increase in drift. Curves between the ratio of in-plane yield capacity and design shear load of walls are proposed for the backfill density, which may be adopted to determine the in-plane yield capacity of the basement walls based on their design shear.     

Seismic behavior of geosynthetic-reinforced retaining walls backfilled with cohesive soil

This study investigates the seismic performance of geosynthetic-reinforced modular block retaining walls backfilled with cohesive, fine grained clay-sand soil mixture. Shaking table tests were performed for three ½ scaled (wall height 190 cm) and ¼ scaled model walls to investigate the effects of backfill type, the influence of reinforcement length and reinforcement stiffness effects. The El Centro and Kobe earthquake records of varying amplitudes were used as base acceleration. Displacement of the front wall, accelerations at different locations, strains on the reinforcements, and the visual observations of the facing and the backfill surface were used to evaluate the seismic performance of model walls. The model walls were subjected to rigorous shaking and the walls did not exhibit any stability problems or signs of impending failure. The maximum deformations observed on the models with cohesive backfill was less than half of the deformation of the sand model. The load transfers between the geogrid and cohesive soil was comparable to that of sand and hence the needed reinforcement length was similar as well. As a result; the model walls with cohesive backfills performed within acceptable limits under seismic loading conditions when compared with granular backfilled counterparts.     

杨庄煤矿建下保护煤柱开采影响分析

结合杨庄煤矿364采区Ⅲ642工作面建下保护煤柱开采实例,就充填开采和不充填开采两种方案进行地表下沉的计算分析,并对地表移动和变形参数的合理选取作了总结,结果表明:用充填巷式开采法对建下保护煤柱进行开采取得了较好效果。     

高放废物地质处置库缓冲/回填材料的气体渗透问题研究进展

简要回顾和总结了国内外学者对处置库中的气体形成与渗透机制,注气试验装置与试验方法,以及气体渗透特性等方面的研究成果和最新进展。研究表明,深地质处置库运营过程中会由于金属无氧腐蚀等产生以氢气为主的多组分气体,气体在缓冲/回填材料中主要以对流–扩散渗流、黏性–毛细管两相流、局部膨胀通道渗流和沿宏观裂缝渗流等4种机制渗透。为此,各国学者先后研发了恒体积渗透装置、K0渗透装置、等向应力渗透装置和三轴渗透装置等注气试验装置,采用控制注气流量速率法或控制注气压力法开展了大量注气试验,发现缓冲/回填材料的气体渗透率和特征压力等渗透特性均与其物理性质和边界条件等诸多因素有关。考虑到处置库实际运营工况的复杂性,多场(热–水–化–力)多相(固–液–气)耦合条件下的缓冲/回填材料的气体渗透特性研究将是今后的一个重要工作方向。     

强夯法和振冲法处理松细砂地基的应用比较

结合某松细砂地基加固工程，对低能量强夯法和无填料振冲法处理松细砂地基的适用性及加固效果进行了试验研究，并对它们的适用范围、优缺点进行了比较分析。试验表明，只要采用正确的施工工艺和参数，采用低能量强夯法和无填料振冲法加固饱和松细砂地基都能取得显著效果。     

矿山充填工艺技术的发展及似膏体充填新技术

文章回顾了充填工艺技术的发展历程,分析了各种充填方式的利弊,并对管道输送特性、充填效果进行了定性比较。结合现代充填发展趋势,提出了似膏体充填新思想,论述了似膏体充填的关键技术及研究思路,并对已取得的研究成果作了简要介绍。     

宝山矿井下碎石黄泥胶结充填系统应用及成本分析

结合宝山矿的实际情况建立了碎石黄泥泵送胶结充填系统,从30多组碎石黄泥泵送胶结充填料中选择了7组配比进行强度测试。在满足采矿工艺要求和可泵性、充填体强度的前提下,使用黄泥替代32%的水泥,最终强度只降低0.65 MPa（9.7%）,而充填成本可节约23.78元/m3     

不同配比全尾砂胶结充填体的动态损伤特性

为得到不同配比下某铜矿尾砂胶结充填体的动力学特性及损伤度,对灰砂比分别为1:4、1:6、1:8和1:10,质量浓度为72％的充填体试件开展了相似加载应变率下的常规单轴冲击试验.结果表明:1)加载应变率为30 s-1,灰砂比为1:4和1:6的试件内部胶结力较强,受到冲击荷载后残余强度较高,仅在边缘处出现少量层状剥落,相同...     

磷石膏膏体充填材料强度优化配比试验研究

为研究贵州开磷矿业总公司采用磷石膏和黄磷渣胶结充填采空区的可行性, 在实验室测试了磷石膏及黄磷渣的主要物理化学性质, 制备了不同浓度不同配比的充填料浆, 并测试其坍落度、泌水率和不同龄期的单轴抗压强度。采用正交试验设计优化磷石膏膏体配比, 并采用Mathematica对强度数据进行拟合, 得出本次试验的最优结果为;磷石膏膏体充填料的最优质量比为黄磷渣∶磷石膏=1∶4, 添加CaO质量为5%, 磷石膏膏体质量浓度为67%~68%。在该配比条件下, 磷石膏膏体充填体28 d单轴抗压强度为2.15~3.42 MPa, 可满足矿山安全生产需求, 并显著降低料浆泌水率。     

白象山铁矿河床下开采地表沉降数值模拟分析

针对设计采用嗣后充填采矿法的白象山铁矿的主矿体位于青山河床下的状况,为了保障矿山安全生产,采用数值模拟方法,对矿体、围岩及断层进行建模,对断层采用岩体弱化的方法建立模型,对于重点研究的地表和对结果有影响的断层进行细化网格的划分,并依据设计的连续倾斜进路尾砂充填法对模型进行开采与充填,分析地表沉降情况。通过计算分析,确定了位于地表河流中部即横坐标为400 m处的最大沉降值0.23 m。根据模拟结果,提出了对存在安全隐患的断层注浆加固的处理方法。经过再次运算得出最大沉降值减小到0.15 m,研究结果验证了采矿方法的安全可行性与注浆加固方法的安全有效性。