基于三剪统一强度准则的太沙基地基极限承载力

基于三剪统一强度准则考虑中间主应力影响的特点,对太沙基地基极限承载力计算公式进行了修正。在修正式中,强度准则中的中间主应力效应参数b对地基极限承载力有影响。算例分析表明:当地基土的内摩擦角较大,b取其较大值时;当地基土的内摩擦角较小,b取其较小值时,修正式都能较好地反映地基极限承载力的真实情况。

施工中监理对构造物地基承载力[σ0]检测的方法和体会

针对构造物的地质情况检测其基底承载力[σ0],简单介绍几种检测方法及检测中应注意的事项。

大跨连体超限高层建筑结构设计研究

为解决传统大跨连体超限高层建筑结构基底承载力低的问题,通过建立大跨连体超限高层建筑结构抗力时变模型,计算大跨连体超限高层建筑结构算量,并与抗力时变模型相关联,在此基础上分析大跨连体超限高层建筑结构抗震性,通过限定不同结构混凝土的保护层厚度,完成大跨连体超限高层建筑结构设计。通过设计实例分析,表明设计建筑结构基底承载力更高,能解决传统大跨连体超限高层建筑结构基底承载力低的问题。

两种地基处理措施组合的综合处理方法

在地基承载力标准值不能满足上部荷载要求、并有软弱下卧层的地基上采用两种地基处理措施组合的综合处理方法 ,可提高地基承载力标准值和压缩模量 ,同时可控制高层塔楼的最大沉降量以及高层塔楼与低层裙房之间的沉降差 ,从而极大地节省地基处理费用。文章介绍了一个完整的工程实例 ,并给出了处理后的单桩和单桩复合地基静载荷试验数据和沉降观测数据。

子坝高度对膏体尾矿初期坝坝体稳定性的影响

由于尾矿排放量的急剧增加,有必要在一些尾矿库上筑建子坝,扩大库容,但随着坝体高度的增大,在一定程度上影响了坝体稳定性。为此,以内蒙古某尾矿库为例,首先基于太沙基地基极限承载力公式计算了膏体尾矿沉积固结后具有的承载力以及不同高度的子坝对基底产生的应力;然后利用Geo-studio软件的slope模块分析了膏体尾矿沉积固结后在其上建5,7,9 m高度子坝的坝体稳定性,结果表明,坝体安全系数虽有所降低,但大于1.2,满足现有规范。研究表明:(1)膏体尾矿沉积固结后在垂直方向总体呈现上软下硬的特征,在水平方向呈坝前硬、向库内逐渐变软的特征;(2)子坝越高,在基底产生的应力越大,故该膏体尾矿库所筑的子坝高度不宜超过9 m;(3)待膏体尾矿入库固结后,可在库上继续筑子坝,子坝的高度需经计算方可确定,但膏体尾矿的上部固结速度较慢,若需赶工期,则需进行坝基处理,以达到筑子坝的地基承载力要求;(4)膏体尾矿在未固结之前,应视为软土地基,而膏体尾矿软基处理技术仍需进一步研究。

高压旋喷灌浆技术在水库除险加固工程中的应用

通过对李家川水库坝基渗漏和溢流堰右边墙基地承载力不足问题的分析,提出了解决坝基渗漏和提高基础承载力问题的方法,通过水库除险加固施工和采集试验样品检验,验证了高压旋喷灌浆技术解决水库险情的可行性,为以后此类险情处理提供了经验依据。

Case analysis of piled raft socketed in weak rock

Piles socketed in soft rock were traditionally regarded as end bearing piles, and the loads transferred from superstructure were assumed in design to be shouldered totally by the piles. This paper was designated to deal with the interaction between the piles socketed in weak rock and surrounding soil through field measurement. The pile head reaction and ground pressure under piled raft foundation were monitored, respectively. The analysis of the data measured in situ shows the characteristics of the pile embedded in weak rock are similar to that of friction pile to some extent. The rock socketed pile, together with the surrounding soil, shoulders the weight of the superstructure. It is suggested that soil bearing should be considered in designing the soft rock socketed piles, which can make the design more economical.

Solution to 1-D consolidation of non-homogeneous soft clay

In this work, semi-analytical methods were used to solve the problem of 1-D consolidation of non-homogeneous soft clay with spatially varying coefficients of permeability and compressibility. The semi-analytical solution was programmed and then verified by comparison with the obtained analytical solution of a special case. Based on the results of some computations and comparisons with the 1-D homogeneous consolidation (by Terzaghi) and the 1-D non-linear consolidation theory (by Davis et al.) of soft clay, some diagrams were prepared and the relevant consolidation behavior of non-homogeneous soils is discussed. It was shown that the result obtained differs greatly from Terzaghi’s theory and that of the non-linear consolidation theory when the coefficients of permeability and compressibility vary greatly.

Seismic ultimate bearing capacity of strip footings on slope

The influence of earthquake forces on ultimate bearing capacity of foundations on sloping ground was studied. A solution to seismic ultimate bearing capacity of strip footings on slope was obtained by utilizing pseudo-static analysis method and taking the effect of intermediate principal stress into consideration. Based on limit equilibrium theory, the formulae for computing static bearing capacity factors, Nq, Nc, Nγ, and dynamic bearing capacity factors, Nqd, Ned, Nγd, which are associated with surcharge, cohesion and self-weight of soils respectively, were presented. A great number of analysis calculations were carried out to obtain the relationship curves of the static and dynamic bearing capacity factors versus various calculation parameters. The curves can serve as the practical engineering design. The calculation results also show that when the values of horizontal and vertical seismic coefficients are 0.2, the dynamic bearing capacity factors Nqd, Ned and Nγd, in which the effects of intermediate principal stress are taken into consideration, increase by 4%-42%, 3%-27% and 34%-57%, respectively.

On composite foundation with different vertical reinforcing elements under vertical loading:a physical model testing study

Aphysical model facility was designed, built, and setup for conducting model tests on a composite foundation in a soil ground. The model tests were carried out on a composite foundation with different combinations of vertical reinforcement elements in the same soil ground. Via the analysis of the collected data the characteristics of the composite foundation with different reinforcing elements were obtained, including the characteristics of load-settlement curves, column stresses, stresses of the intercolumn soil, pile-soil stress ratio, and load-sharing ratios of columns and soil. Results from the model tests reveal the mechanism of a composite foundation with different reinforcing elements quantitatively. It is concluded that both a composite foundation with a combination of steel pipe pile and sand column and that with a combination of concrete pile and lime column have a higher bearing capacity than the composite foundation with only sand columns with the same conditions of soil ground and loading. A composite foundation with lime column and sand column embodies no much better performance than that with sand colunms only.