煤矿复合破碎软岩大断面巷道破坏机理与支护对策初探

通过分析煤矿复合破碎软岩大断面巷道破坏机理,将控制机理完全揭示,对相应的支护措施也提出了更科学的方法,对于支护过程中的各种参数以及施工过程中采用的工艺都进行了优化。在具体工程中的实践说明该技术有良好的成效,也因这些科学措施获得了更高的经济效益,希望本文对类似工程有借鉴作用。

和田地区道面损坏机理与盐渍土工程特性研究

为解决新疆和田地区盐渍土对机场道面损坏严重的问题,对和田机场的道面状况和土样特性进行了实地调查和室内试验,分析表明:道面损坏形式主要有鼓胀、错台和断板。主要原因是道面结构层中的某一层(多数为水泥稳定砂砾层)发生盐胀,且以硫酸盐为主。通过调整干密度、硫酸钠含量、含水量并进行盐胀试验,分析了这3种因素的影响规律,结果表明:随着土的干密度增大,土体盐冻胀力增大;随着硫酸钠含量增加,土体盐冻胀力增大,且以硫酸钠含量1%为界,小于1%时盐冻胀力增长缓慢,大于1%则增长迅速;随着含水量增大,盐冻胀力存在极值,且在最优含水量时盐冻胀力达到最大,这与最优含水量击实理论一致。

超高压水射流道路除标线试验研究

超高压水射流道路标志线清洗是目前最为有效的标志线清洗工艺。该研究对超高压水射流除标线的影响因素及机理进行了研究。实验研究了水射流压力、旋转接头转速、靶距、执行机构移动速度4个因素对清除标线效果的影响规律。研究表明,超高压水射流道路除标线存在最优靶距和最优旋转接头转动速度。从微观角度分析了道路标线破坏的机理。研究为道路除标线提供优化的参数匹配,为我国超高压水射流道路除标线提供参考依据。

Model test to investigate failure mechanism and loading characteristics of shallow-bias tunnels with small clear distance

Based on the similarity theory,a tunnel excavation simulation testing system under typical unsymmetrical loading conditions was established.Using this system,the failure mechanism of surrounding rock of shallow-bias tunnels with small clear distance was analyzed along with the load characteristics.The results show that:1) The failure process of surrounding rock of shallow-bias tunnels with small clear distance consists of structural and stratum deformation induced by tunnel excavation; Microfracture surfaces are formed in the tunnel surrounding rock and extend deep into the rock mass in a larger density; Tensile cracking occurs in shallow position on the deep-buried side,with shear slip in deep rock mass.In the meantime,rapid deformation and slip take place on the shallow-buried side until the surrounding rocks totally collapse.The production and development of micro-fracture surfaces in the tunnel surrounding rock and tensile cracking in the shallow position on the deep-buried side represent the key stages of failure.2) The final failure mode is featured by an inverted conical fracture with tunnel arch as its top and the slope at tunnel entrance slope as its bottom.The range of failure on the deep-buried side is significantly larger than that on the shallow-buried side.Such difference becomes more prominent with the increasing bias angle.What distinguishes it from the "linear fracture surface" model is that the model proposed has a larger fracture angle on the two sides.Moreover,the bottom of the fracture is located at the springing line of tunnel arch.3) The total vertical load increases with bias angle.Compared with the existing methods,the unsymmetrical loading effect in measurement is more prominent.At last,countermeasures are proposed according to the analysis results: during engineering process,1) The surrounding rock mass on the deep-buried side should be reinforced apart from the tunnel surrounding rock for shallow-buried tunnels with small clear distance; moreover,the scope of consolidation should go beyond the midline of tunnel(along the direction of the top of slope) by 4 excavation spans of single tunnel.2) It is necessary to modify the load value of shallow-bias tunnels with small clear distance.

Analysis of soft rock mineral components and roadway failure mechanism

The mineral components and microstructure of soft rock sampled from roadway floor in Xiagou pit are determined by X ray diffraction and scanning electron microscope. Combined with the test of expansion and water softening property of the soft rock, the roadway failure mechanism is analyzed, and the reasonable repair supporting principle of roadway is put forward.

Catastrophe stability analysis for shallow tunnels considering settlement

Limit analysis of the stability of geomechanical projects is one of the most difficult problems.This work investigates the influences of different parameters in NL failure strength on possible collapsing block shapes of single and twin shallow tunnels with considering the effects of surface settlement.Upper bound solutions derived by functional catastrophe theory are used for describing the distinct characteristics of falling blocks of different parts in twin tunnels.Furthermore the analytical solutions of minimum supporting pressures in shallow tunnels are obtained by the help of the variational principle.Lastly,the comparisons are made both in collapsed mechanism and stability factor with different methods.According to the numerical results in this work,the influences of different parameters on the size of collapsing block are presented in the tables and the limit supporting loads are illustrated in the form graphs that account for the surface settlement.

Failure mechanism and control technology of water-immersed roadway in high-stress and soft rock in a deep mine

Aiming at soft rock ground support issues under conditions of high stress and long-term water immersion, the ground failure mechanism is revealed by taking the deep-water sumps of Jiulong Mine as the engineering background and employing field investigation, tests of rock structure, mechanical properties and mineral composition. The main factors leading to the surrounding rock failure include the high and complex stress state of the water sumps, high-clay content and water-weakened rock, and the unreasonable support design. In this paper, the broken and fractured rock mass near roadway opening is considered as ground small-structure, and deep stable rock mass as ground large-structure. A support technology focusing on cutting off the water, strengthening the small structure of the rock and transferring the large structure of the rock is proposed. The proposed support technology of interconnecting the large and small structures, based on high-strength bolts, high-stiffness shotcrete layer plugging water,strengthening the small structure with deep-hole grouting and shallow-hole grouting, highpretensioned cables tensioned twice to make the large and small structures bearing the pressure evenly,channel-steel and high-pretensioned cables are used to control floor heave. The numerical simulation and field test show that this support system can control the rock deformation of the water sumps and provide technical support to similar roadway support designs.