深厚表土中立井井壁水平地压力计算探讨

基于石集立井实测水平地压力,对比分析了当前常见的几种水平地压力计算理论的准确性与适用性。分析表明,我国立井井筒设计规范建议的计算水平地压力的重液公式的计算结果与实测值误差很大,其计算均值是实测均值的100倍以上。以浅部土力学思路建立的水平地压力具有随着深度的增加而增大的特征。而深厚表土中的水平地压力分布规律可能与此不同,其压力值最终趋于稳定,不会无限制的增大。由于固结时间、应力水平、应力路径的不同,深厚表土层的物理力学性质与浅部土体具有显著差异。建议深入开展深土力学研究,基于更多的测试与研究工作来确定深厚表土中水平地压力的大小与分布规律。

深厚表土水平地压计算方法分析与探讨

考虑由于深部土的力学特性和深部水平土压产生机理不同于浅部,用于深部水平土压现行计算方法存有缺陷。该文分析了K0值计算深土水平地压方法存在的问题,提出结构与土耦合作用对深土水平地压影响不可忽视,应展开深入研究,完善深部岩土工程水平地压计算方法。这对当前我国资源开采,竖井安全建设无疑具有非常重要的意义。

测力锚杆对金属矿深立井地压的监测与结果分析

为研究金属矿深立井地压的分布规律,在新城金矿新主井凿井过程中,采用改进的新型地压监测装置测力锚杆,更为精准地开展了立井地压的现场实测。监测数据表明:测力锚杆能够适应立井地压周期长、腐蚀强、淋水严重的复杂监测环境,工程应用性较强;金属矿立井地压以压力为主同时局部出现拉力,地压分布表现出不均匀性;井壁受拉部位,井壁所受围岩拉力约0.2MPa,岩层稳定,裂隙不发育部位,井壁水平压力约为0.06MPa,同一水平,裂隙发育部位,井壁水平压力约为3.6MPa,裂隙发育部位围岩对井壁的水平压力是稳定岩层中围岩对井壁水平压力的60倍左右;与埋深浅的矿井相比,深部金属矿井筒埋深大,在裂隙发育部位,水压值更大,井壁受到围岩较大的水平压力,且水平压力不稳定。

Calculation method of first collapse span with superhigh water material backfill mining

It is critical for the material to be of active supporting capacity before initial collapse ot mare root wltn supermgn water material backfill mining, and the maximum bending moment should be first calculated in order to determine the initial collapse span. In the light of principal of virtual work, the simple expression of deflection, bending moment of elastic clamped plate were deduced under the condition of vertical uniform distributed load, horizontal pressure and supporting by elastic foundation, and then, the maximal bending moment expression was derived too. At the same time, the influence degree on square clamped plate by adding horizontal pressure and elastic foundation were analyzed. The results show that the effect of horizontal pressure on maximal bending moment can be ignored when the value of horizontal pressure is two orders of magni- tude less than that of coeificient of elastic stiffness existing elastic foundation.

Equilibrating Pressure with Auto-Control Valve in Water Distribution Networks

This paper probes into the feasibility of equilibrating pressure of water distribution network through (using auto-control valves) in theory and in the economy. An optimal valve control model is designed to minimize the sum of squares of residual pressure in the network. Such an analog simulation has been performed on the year 2003 programming network of a certain littoral district in North China, through which this paper confirms that it is feasible to equilibrate pressure with auto-control valves in theory. The research work has brought about a discovery of applicable conditions of valves in economic feasibility, which avoids a great economic loss due to the wild use of auto-control valve. In addition, simulated annealing algorithm is applied to optimize valve settings and shown to identify global optimum or near-optimum.

The Drainage Exchange of Stormwater Potential in Flat Area Problems

Groundwater as an alternative source still does not contribute to the water supply in area of Parit Raja because of the limitation of water availability in the ground. This lacking of groundwater could be caused by the circumstance that the top layer of soil is dominated by compacted clay around 2 meters in which its permeability is small, so the water is difficult to infiltrate the ground. The recharge well technique was designed based on the flat area problems, layer of real condition, flow water table and low infiltration rate. Resistivity soundings were made at existing wells to assess the subsurface layers. Beside that, the past records on floods event, sub surface and surface studies were collected around study area as a preliminary studies. It was presented that the study area promised good prospects to increase the capability of groundwater and contribute to the drainage system by reducing the volume of rainfall runoff using the recharge well technique.

Mechanical Response of Saturated Geological Rock Mass under Tidal Force

In this paper, the mechanical response of saturated geological rock under tidal force is explored by poroelastic theory. First, we use the free energy formula of saturated rock under a tidal force to study the relationships of pore pressure with stress, and stress with strain. Then we analyze the relationship between rock strain and tidal potential by the equilibrium differential equations of saturated rock under tidal force. Finally, we derive the physical relationship between the two parameters （pore pressure and tidal mean stress） of saturated rock and tidal potential. The relationship shows that：pore pressure is directly proportional with tidal potential, but tidal mean stress of saturated rock is inversely proportional with tidal potential. The ratio coefficient is related not only to the Lame coefficients of rock skeletons, but also to the Blot modulus. By using this model to analyze observational well water level of C-18 well which locates in Huili, Sichuan Province, the well level response coefficient （D） was estimated. This way, we derive the Skempton coefficient （B）, the coefficient A and C which refer to the response coefficients of pore pressure and tidal stress to tidal potential respectively. Then we compare the differences among each coefficient in coupling and uncoupling conditions. It shows that for saturated rocks, the response of stress and pore pressure to earth tides is a product of coupling, and it is necessary to take into account the coupling effect when we study the mechanical response. The model will provide the basis not only for the study of mechanics and hydrodynamics of well-confined aquifer systems, and the mechanics of faulting under tidal force, but also for quantitative research of the triggering mechanism of tidal forces.

Examination of DMT-based methods for evaluating the liquefaction potential of soils

The flat dilatometer test （DMT） has the potential to be a useful tool in the evaluation of liquefaction potential of soils. In practice, it is necessary to carefully examine existing DMT-based methods for evaluating liquefaction potential. We con- ducted the DMT and cone penetration test （CPT） in high liquefaction potential areas to examine the existing DMT-based methods for liquefaction potential evaluation. Specifically, the DMT and CPT were conducted side-by-side at each of six in-situ sites, and thus it is feasible to utilize those test results to validate the existing DMT-based methods. The DMT parameter, horizontal stress index （KD）, is used as an indicator for estimating liquefaction resistance of soils in terms of cyclic resistance ratio （CRR）. The analysis results revealed that the existing KD-based liquefaction evaluation methods would overestimate the CRR of soils, which leads to overestimation of the factor of safety against liquefaction. Also, the estimations of DMT-KI~ values by using the CPT-qc as well as the correlation between DMT-KD and CPT-qc proposed by the previous studies would be significantly smaller than field measurements. The results reflected that further validation of the existing DMT-based methods for liquefaction evaluation is desirable.