准固结粘土排水试验的应力性状研究

软粘土在恒定的静力压力下经一段时间后可形成准前固结效应，其三轴排水试验结果代表有效应力屈服面，本文依据莫尔－库仑屈服条件，将不规则的主角形截面的角锥体屈服面简化为具有二次式的椭园式屈服面，进而可确定粘土的孔隙压力和变形，亦可方便地用于有限元程序求争实际边界值问题。

深覆盖层上面板堆石坝防渗墙应力变形性状影响因素的研究

采用数值分析方法对深覆盖层上混凝土面板堆石坝的防渗墙应力变形性状进行了研究。研究了覆盖层特性、防渗墙混凝土特性、防渗墙施工顺序、防渗墙与坝趾之间距离和防渗墙形状对于面板堆石坝防渗墙应力变形性状的影响。总结出一些规律并提出相应的工程建议。

减P路径下饱和软粘土应力应变性状的试验研究

对汉口某地的淤泥质粘土进行了一系列应力路径试验。试验表明,饱和软粘土的应力应变性状与应力路径密切相关,在各种减P应力路径下的应力比与轴应变之间均存在着良好的双曲线关系,据此,建立了一个和应力路径有关的归一化应力应变双曲线模型。分析了排水试验中的体变特性和不排水试验下的孔压变化特性。

预应力桩水平承载性状数值分析

预应力桩广泛应用于建筑物桩基础中,单桩水平承载力由于受力条件复杂难以确定。利用大型有限元软件ABAQUS,采用混凝土塑性损伤模型模拟预应力桩水平承载性状,选取上海典型场地软土试桩验证后,进一步分析灌芯以及桩型对水平承载力影响。分析表明:数值计算方法能有效模拟H-y曲线陡降变形,全过程反映预应力桩的水平承载性状;配筋灌芯对单桩承载力影响不大,但能一定程度改善H-y曲线陡降变形;桩型变化对单桩水平承载力影响不大,但能够延缓H-y曲线陡降变形,提高桩身延性。

主应力方向和中主应力系数对冻结黏土性状的影响

为研究复杂应力路径下冻土的力学特性,利用冻土空心圆柱仪对饱和冻结黏土开展了定向剪切试验,重点研究了大主应力方向和中主应力系数对饱和冻结黏土应力应变性状的影响.试验结果表明:定向剪切路径下饱和冻结黏土应力-应变曲线基本呈现应变硬化特征,且广义剪应力-应变曲线受扭剪分量的主导.不同大主应力方向下冻结黏土应力-应变曲线水平存在一定差异,当中主应力系数b为0.5和1时广义剪应力-应变曲线水平随着大主应力方向角α的增加而降低.中主应力系数b对冻结黏土扭剪分量的应力应变性状影响相对较小,而对轴向分量与广义剪应力应变性状影响显著.

防渗墙施工工序对墙体应力变形影响规律的研究

结合实际工程,采用非线性有限单元法,开展深覆盖层混凝土面板堆石坝防渗墙应力变形性状研究,分别对比分析3种不同施工工序情况下防渗墙在竣工期和蓄水期应力变形性状,总结出防渗墙的相关应力变形规律,并给出了相应工程建议,具有较为重要的学术意义与工程应用价值。

条基-疏桩现场实测试验研究

条基-疏桩复合基础是一种新型的桩基形式,介绍了其在某住宅小区的应用,阐述了试验模型、加载系统及测试系统的设计,通过有说明力的现场实测数据分析了条基-疏桩的承载性能,研究了条基-疏桩复合基础的荷载-位移性状、条基的位移及应力性状、桩的轴力分布以及条基-疏桩的荷载分担比。为疏桩的理论研究和设计工作提供了实测对比资料。

深厚覆盖层上面板堆石坝新型结构应力变形性状影响因素研究

建设在深厚覆盖层上的高混凝凝土面板堆石坝防渗体系通常采用趾板水平连接混凝土面板和防渗墙,为缩短工期和节省工程投资,建议采用在坝基面处挖除表层部分覆盖层,浇筑混凝土盖板,在盖板内部留有廊道,以便进行防渗墙施工,同时上部填筑坝体的新型结构。采用有限元法对深厚覆盖层上混凝土面板堆石坝新型结构的应力变形性状进行研究。研究盖板长度、盖板分缝、坝基覆盖层加固对面板堆石坝坝体、面板、防渗墙应力变形性状的影响。

聚丙烯纤维复合土抗裂补强特性试验研究

将聚丙烯纤维按不同类型、不同组合、不同含量掺入土中的三轴压缩试验,研究了聚丙烯纤维复合土的应力-应变性状及对复合土强度特性的影响。试验结果表明,加固黏性土要选择分散性好的束状单丝聚丙烯纤维,而不是网状聚丙烯纤维,聚丙烯纤维按占土质量0.2%时为最佳掺入量,束状单丝聚丙烯纤维长度为6 mm+10 mm+15 mm+19 mm的4种组合较为理想,可使聚丙烯纤维复合土微结构联结强度得到明显改善,抗裂补强,黏性土抗剪强度得到极大的提高。

深覆盖层上面板堆石坝的圆弧型防渗墙

覆盖层的防渗设施大都采用混凝土防渗墙。防渗墙在靠近两岸部位及靠近顶部常存在较大的拉应力,易导致混凝土开裂并产生渗漏,影响大坝的安全。采用平面上防渗墙轴线呈圆弧型的防渗墙来改善防渗墙的应力性状,并用三维有限元法数值分析对圆弧型防渗墙与直线型防渗墙的应力变形性状进行分析比较,论证了以圆弧型防渗墙替代直线型防渗墙的技术合理性,建议面板堆石坝坝基防渗采用圆弧型防渗墙更为有利。

纤维增强水泥土力学性能试验研究

纤维加筋技术是一种新式的改良土体方法,能够有效地提高土体力学性能。选取聚丙烯纤维和水泥作为加筋稳定材料,将纤维的物理加筋作用和水泥的化学加固作用相结合,开展无侧限抗压强度(UCS)试验,研究了纤维加筋稳定土的强度力学特性与应力-应变性状。通过试验,研究了不同水泥掺量(6%、8%、10%)、纤维掺量(0.15%、0.3%、0.45%)及不同龄期(3 d、7 d、14 d)对试样强度的影响。试验结果表明,水泥和纤维的掺入均能够提高土体的强度,纤维的加入使纤维加筋水泥土试样由脆性破坏模式向塑性破坏模式转变。

Study of electromagnetic characteristics of stress distribution and sudden changes in the mining of gob-surrounded coal face

The incidence of dynamic coal or rock disasters is closely related to the distribution of stress in the surrounding rock. Our experiments show that electromagnetic radiation （EMR） signals are related to the state of stress of a coal body. The higher the stress, the more intense the deformation and fractures of a coal body and the stronger the EMR signals. EMR signals reflect the degrees of concentrated stress of a coal body and danger of a rock burst. We selected EMR intensity as the test index of the No.237 gob-surrounded coal face in the Nanshan coal mine. We tested the EMR characteristics of the stress distribution on the strike, on the incline and in the interior of the coal body. The EMR rule of rock bursts, caused by sudden changes in stress, is analyzed. Our research shows that EMR technology can be not only used to test qualitatively the stress distribution of the surrounding rock, but also to predict a possible occurrence of rock burst. Based on this, effective distress measures are used to eliminate or at least weaken the incidence of rock bursts. We hooe that safetv in coalmines will be enhanced.

Stability and remote real-time monitoring of the slope slide body in the Luoshan mining area

Landslides have occurred frequently in the Luoshan mining area because of disordered mining.This paper discusses the landforms and physiognomy,hydro-meteorology,formation lithology,and geologic structure of the Luoshan mining area.It also describes the factors influencing the slope stability of landslide No.Ⅲ,determines the general parameters and typical section plane,analyzes the stress-strain state of the No.Ⅲ slope,and calculates its safety factors with FLAC3 D under saturated and natural conditions.Based on a stability analysis,a remote real-time monitoring system was applied to the No.Ⅲ slope,and these monitoring data were collected and analyzed.

Experimental study of seepage characteristics of single rock fracture based on stress states and stress history

Through seepage tests under different loading and unloading confining pressures and different hydraulic gradients,the authors studied the effects of stress states and stress history on fracture permeability evolution for single granite fracture and sandstone fracture. The results show that there exists a linear relationship between the seepage discharge and osmotic pressure in sandstone fissure under each level of confining pressure. With the increasing in the confining pressure,the permeability of the fracture decreases,but the decreasing rate is changeing. During the unloading process,the fracture seepage velocity cannot be fully recovered to the size of the loading process. Therefore,in the unloading process of the confining pressure,the recovery of fracture permeability shows obvious hysteresis effects. The flow rate of the fracture remains unchanged during five cycles of loading and unloading processes of the confining pressure. In each cycle,the evolution character of the flow rate with the confining pressure remains unchanged. These experiments show that the seepage characteristics of sandstone and granite fractures are not the same under the same stress state.

渔洞水库重力坝抗震分析

渔洞水库大坝在云南省已建重力坝中坝高为第二位，本文较为详细地分析了该大坝在７０地震作用下的应力应变性状、动力稳定性及其可能的破损部分，为该工程的设计、施工提供了科学依据。分析结果也可供类似工程设计、施工时参考。

Effect of discontinuities characteristics on coal mine stability and sustainability： A rock fall prediction approach

Rock fall related accidents continue to occur in coal mines,although artificial support mechanisms have been used extensively. Roof stability is primarily determined in many underground mines by a limited number of methods that often resort to subjective criteria. It is argued in this paper that stability conditions of mine roof strata,as a key factor in sustainability in coal mines,must be determined by a survey which proactively investigates fundamental aspects of said mine. Failure of rock around the opening happens as a result of both high rock stress conditions and the presence of structural discontinuities. The properties of such discontinuities affect the engineering behavior of rock masses causing wedges or blocks to fall from the roof or sliding out of the walls. A practical rule-based approach to assess the risk of a roof fall is proposed in the paper. The method is based on the analysis of structural data and the geometry and stability of wedges in underground coal mines. In this regard,an accident causing a huge collapse in a coal mine leading to 4 fatalities is illustrated by way of a case study. Horizontal and vertical profiles are prepared by geophysical methods to define the falling zone and its boundaries. The collapse is then modeled by the use of sophisticated computer programs in order to identify the causes of the accident.

Analysis of faults stability with dynamic phenomena in the mice based on slide criterion and in-situ stress measurement

For the study on the relationshl＇p between the dynamic phenomena in the mining such as mine earthquakes, outburst and faults slide, firstly, double shear friction experiments of sandstone were made, and its slide criterion was suggested considering the viewing of engineering. Secondly, in order to study the stability of underground rock and zone of tectonic stress field, based on the analysis on distribution characteristic of initial rock stress measurements, the geology structural model was built and tectonic stress field was made a back-analysis by applying finite element method. The calculating results fit with the analysis result of earthquakes mechanism and the distribution characteristic of the measurements. The high stress regional centers station locates discontinuous zone of I level faults and is corresponding to underground earthquakes scene. From then it is certain that tectonic stress is the major origin and necessary condition of mine earthquakes. The instability slide of the faults is the main manifest and the mining activity is the leading factor. Beipiao fault has a dominate effect on other sub faults and tectonic stress area and is dynamical fountain of dynamic phenomena in the Beipiao Mines.

Experimental research on hydrophilic characteristics of natural soft rock at high stress state

In order to study features of rock–water interaction, a self-developed experimental system called Intelligent Testing System for Water Absorption in Deep Soft Rocks(ITSWADSR) was utilized to analyze the hydrophilic behaviors of natural soft rock at high stress state. Combining X-ray diffraction and mercury injection test, main influencing factors on hydrophilic characteristics were studied. According to the results, it could be concluded as the following:(1) the effective porosity, and the content of illite, illite/smectite formation(S = 5%) and kaolinite have positive correlation with the water absorption capacity of rock; meanwhile, the initial moisture content, fractal dimension of effective pores, illite/smectite formation(S = 30%) and chlorite present negative correlation;(2) among the positive factors, the ascending order is kaolinite, illite/smectite formation(S = 5%) and illite;(3) the descending order among the negative factors are chlorite, illite/smectite formation(S = 30%) and fractal dimension of the effective pores;(4) influence of effective porosity on the pressurized water absorbing capacity of rock is minimal, while it is maximal in the process of no pressurized water absorption.

Analysis of the mechanic characteristics of the damage propagation of rock under triaxial stress condition

The advanced computerized tomography is applied to study the damage propagation of rock. The real time CT scanning is carried out to the damage propagation of rock under triaxial stress condition. The damage propagation constitutive relation of rock under triaxial stress condition is analyzed at last.

3D Finite Element Simulation of Tunnel Boring Machine Construction Processes in Deep Water Conveyance Tunnel

Applying stiffness migration method,a 3D finite element mechanical model is established to simulate the excavation and advance processes.By using 3D nonlinear finite element method,the tunnel boring machine(TBM) excavation process is dynamically simulated to analyze the stress and strain field status of surrounding rock and segment.The maximum tensile stress of segment ring caused by tunnel construction mainly lies in arch bottom and presents zonal distribution.The stress increases slightly and limitedly in the course of excavation.The maximum and minimum displacements of segment,manifesting as zonal distribution,distribute in arch bottom and vault respectively.The displacements slightly increase with the advance of TBM and gradually tend to stability.