土钉墙凭借一些显著的优越性被广泛应用于基坑工程的开挖支护，并带来了巨大的社会和经济效益。然而，国内存在大量盲目使用土钉墙的现象，由于没有认清适用范围，加上设计和施工中存在大量的问题，导致基坑安全事故屡见不鲜。因此需要全面认识土钉墙的作用机理，了解土钉墙的优缺点、重视其施工水平。针对土钉墙在岩土工程应用中存在的问题做了详细讨论，并提出了改进方法和土钉墙今后研究的方向，对土钉墙的耐久性、抗震、蠕变以及无损检测、变形的预测、复合土钉墙等方面展开研究将具有非常深远的意义和良好的发展前景。

Soil nail wall is widely used in supporting foundation pit excavation and brings great social and economic benefits. However, soil nail wall is blindly used in China at present. People are not aware of its limitations and applicable scope, giving rise to problems in the designing and construction which lead to lots of accidents. In view of this, we should have a comprehensive understanding of the action mechanism of soil nail wall. At the same time, we need to understand its superiorities and limitations and pay attention to its construction. This paper lays emphasize on problems in the use of soil nail wall, and gives advices to make it better. What’s more, we discuss the future use of soil nail wall, for example, the durability of soil nail wall, anti-seismic resistance, creep deformation, nondestructive examination, deformation estimation, composite soil nail wall and so on. Research on these aspects will be of far-reaching and promising importance.

基于朗肯土压力理论研究了土钉墙的主要设计参数对边坡安全性的影响。通过建立土钉安设位置及安设角度与边坡安全系数间的函数关系,从数学角度确定了高边坡和低边坡的界限值,分析了土钉安设位置、安设角度、边坡土黏聚力、内摩擦角4个主要因素对边坡安全性的影响,得到了高边坡情况下土钉安设位置及安设角度与边坡安全性负相关,低边坡条件下土钉安设位置及安设角度与边坡安全性正相关以及当边坡土质很差时不应采用土钉加固方案的结论。

On the basis of Ranking’s earth pressure theory and by mathematical analysis method, the effects of main design parameters of soil nail wall on the slope safety were studied. Through the establishment of a function between the safety factor and installed position, setting angle of soil nailing, the problems of boundaries in high slope and low slope were put forward, the influence of four main factors as the soil nailing setting position and angle, slope soil cohesive force and internal friction angle on the slope safety was considered. Three main conclusions have been drawn: soil nailing installed position and angle is negatively related to the safety in the condition of high slope, soil nailing installed position and angle is positively related to the safety in the condition of low slope and soil nail reinforcement scheme should not be adopted when the slope soil property is very poor.

针对目前土钉墙设计参数进行优化设计只是在给定土体强度下进行的,且其优化算法仍有些缺陷,而在不同粘聚力c、内摩擦角φ下,研究分析土钉墙参数选取及经济性也具有重要的理论和实际意义。从不同土体强度出发,以单位墙长土钉墙工程造价为目标函数,按规范要求设置约束条件,建立了不同土体强度对土钉墙设计参数及经济性影响的计算模型,并应用嵌套的改进的遗传算法求解,得到土体强度与土钉墙设计参数、土体强度与土钉墙经济性的关系曲线,并对其计算结果进行分析。所得结论可为土钉墙参数设计选取及经济性分析提供理论支持。

Parameters selection and economy of soil nailing wall would be comprehensively analyzed under different cohesive force <i>c</i> and angle of internal friction <i>φ</i>, which can contribute to engineering design and theoretical research. However, the research for the optimization of soil nailing wall design parameters is carried out only under the permanent strength value of soil at present, they cannot meet the requirement of engineering practice. Furthermore, in the optimization algorithm there are also some imperfection. Taking different soil strength, a calculation model was established to analyze design parameters and economy of soil nailing wall, the construction cost was used to build objective function and the constraint condition was set according to the soil nail specification. A new way, the nested and modified Genetic algorithm was proposed to solve the problem. Through the way given above, the relative curve of the soil strength with the parameters of the soil nail wall, as well as the relationship between the soil strength and the economy of the soil nail wall were obtained in this paper. The conclusion can offer theoretical support for parameters selection and economic analysis of soil nailing wall.

边坡抗滑桩桩间土拱效应对桩间土钉墙各部分的受力及土钉的设计长度有重要影响，然而现阶段多依个人或者设计单位经验对桩间土钉墙各部分的受力进行计算，对土钉长度进行设计，以上传统的受力计算及土钉设计方法均未充分考虑土拱的影响，使得土拱在工程运用中受到了限制。为了推广土拱在工程中的运用，首先描述土拱形状，继而深入研究土拱对桩间土钉墙各部分受力的影响，提出了基于土拱效应桩间土钉墙受力计算方法和土钉长度设计方法，此受力计算方法认为：土钉墙的受力取拱前土体主动土压力或剩余下滑力两者中的较大者，抗滑桩的受力为拱后土体剩余下滑力与土钉墙受力之和，土钉长度设计中土钉自由段和锚固段的分界线为土拱迹线。继而结合巴（中）达（州）铁路堑坡，通过数值模拟描述土拱形状，计算土拱影响下不同截面处抗滑桩和土钉墙的受力，并结合土拱形状对土钉长度进行设计，与不考虑土拱效应时受力计算结果和土钉长度设计结果进行对比。研究结果表明：考虑土拱效应较不考虑土拱效应时，抗滑桩纵断面受力明显增大，增幅大于11%，土钉墙纵断面受力明显减小，减幅大于12%，土钉用量节省接近13%，充分说明考虑土拱效应确实对抗滑桩受力、土钉墙受力和土钉设计长度造成较大影响。

The soil arching effect between piles has an important effect on the force acting on various parts of a soil nailing wall between piles and the design length of the soil nails. However, at this stage, the force calculations on each part of the soil nailing wall between piles and the design length of the soil nail are often based on the experience of individuals or design units. The traditional force calculation and soil nail design methods do not fully consider the effect of soil arching, which limits soil arching in engineering applications. To promote the application of soil arching in engineering, this paper first describes the shape of soil arching and then studies the effect of soil arching on the force induced on various parts of the soil nailing wall between piles. Based on the soil arching effect, a force calculation method for the soil nailing wall between piles and a design method for soil nail length are proposed. The force calculation method considers that the force on the soil nailing wall is the greater force between active earth pressure before the soil arching and the residual sliding force before the soil arching. The force on the stabilizing pile is the sum of the residual sliding force due to the soil mass behind the soil arching and the force on the soil nailing wall. In the design of soil nail length, the boundary between the free section and the anchor section of the soil nail is the soil arching trace. Then, combined with the cut slope of the railroad in the Bazhong-Dazhou Railway, the shape of soil arching was determined through a numerical simulation, and under the effect of soil arching, the forces on the stabilizing piles and soil nailing walls at different cross-sections were calculated. The length of the soil nail was designed in combination with the shape of soil arching. The results of force calculations and soil nail design length were compared with the results before and after the consideration of the soil arching effect. The results indicate that compared to the case without considering the soil arching effect, when the soil arching effect is considered, the force on the vertical section of the stabilizing pile significantly increases by more than 11%. The force on the vertical section of the soil nailing wall significantly decreases by more than 12%, and the amount of material used in the soil nail reduces by approximately 13%. This clearly demonstrates that considering the soil arching effect does have a great impact on the force on the stabilizing pile, the force on the soil nailing wall, and the design length of the soil nail.

通过控制含水量的粉土与土-钉界面拉拔剪切室内试验,研究不同土体含水量及上覆压力时,钉-土界面的剪切应力与剪切位移关系、界面剪切强度及表观摩擦系数的变化规律。试验结果表明:钉-土界面剪切应力随上覆压力的增加而显著增加,峰值剪切应力对应的拉拔位移也逐渐增大,且剪切应力达到峰值后出现软化现象;钉-土界面的剪切应力与土体含水量呈负相关;峰值、残余剪切应力均随着上覆压力的增大近似呈线性增加,随着土体含水量的增大而显著下降;峰值应力与残余剪切应力的差值随着土体含水量的增加而减小,随着上覆压力的增加而增大。研究成果可为土钉拉拔承载性能研究提供参考。

The formula of determining the critical angle of soil self-stabilizing is deduced based on upper bound theorem. A new method is presented to evaluate slope stability by using the ratio of soil self-stabilizing angle to slope angle. In addition to the known second slip surface, which is the potential slip surface involving the overall stability, a new slip surface, namely the first slip surface is testified to possibly exist in the active zones of soil nail walls for the first time. This slip surface is determined by soil self-stabilizing angle. A series of case studies have validated the method proposed in this study. This research reveals the mechanism of soil slide, and provides a new approach of determining the stability of slope and soil-nail wall.