大锚杆微型桩在顺层岩质边坡上的应用

中厚层或厚层软、硬相间互层岩体的破坏模式一般是沿软弱结构面发生顺层滑移破坏。鉴于此深入分析大锚杆微型桩在顺层岩质边坡的受力机理,并将该理论方法应用于织纳高速公路某段顺层岩质边坡上,提高了边坡的可靠度,加快了施工进度。

掘锚一体大锚杆施工工艺在门克庆煤矿的应用

为实现煤巷快速掘进技术和工艺的进一步突破,解决中天合创煤炭分公司对煤巷高效快速掘进的需求,实现提效降本,提高企业竞争力,中天合创门克庆煤矿11-3103工作面带式输送机巷拟采用掘锚机配合大锚杆支护技术支护顶板。掘锚机能够保证对顶板的及时支护,安全系数较高。此外,掘锚机自带帮部锚杆机,实现掘、锚同步,能够有效防止帮部片帮发生。大锚杆支护技术是新的支护形式,在充分论证满足顶板支护强度的条件下,扩大了巷道支护间排距,缩短了支护时间,实现掘锚一体配合大锚杆支护技术在门克庆煤矿深井煤巷的成功应用,并实现月总进尺1050m,日最高进尺46. 5m,创造了蒙陕矿区深井掘锚工艺单进新纪录。

大锚杆加固顺层石质路堑边坡施工技术

结合某公路边坡支护案例,鉴于该项目存在较多顺层岩石地段以及存在山体滑动可能性,综合比较选取锚杆支护方案,采取光面爆破开挖施工、对路垫边坡进行加固等一系列措施。从本工程实施效果表明,经锚杆支护后的公路边坡滑动趋势得到有效控制,表明该支护方案的可行性,可在同类工程中应用。

大锚杆加固顺层石质路堑边坡施工技术

以渝怀铁路某段右侧顺层路堑边坡为例，从施工准备、钻孔、锚杆制作及安装等方面，对锚杆加固施工工艺进行了详细介绍，实践证明，采用大锚杆对边坡进行锚固，整治效果好，工艺简单，社会经济效益显著。

大锚杆联合抗滑桩在顺层边坡支挡的应用

顺层边坡问题是山区高速公路建设中常见的岩土工程问题,本文对顺层边坡的支护手段进行比较分析,结合一工程实例,论述大锚杆联合抗滑桩治理顺层边坡的合理性。该方法对指导设计、施工具有现实意义。

锚杆加固顺层路堑高边坡技术研究

以贵广铁路某段左侧顺层路堑边坡施工为例,从施工准备,钻孔、锚杆制作及安装等方面,对锚杆加固施工工艺进行了详细介绍,经过现场施工证明,采用大锚杆对边坡进行锚固,治理的效果较好,施工工艺简单,经济效益显著。

岩石顺层路堑边坡加固方案研究

介绍渝怀铁路顺层路堑工点的设计和加固处理措施 ,重点阐述大锚杆、锚索加固边坡的设计。

深井大松动圈软岩巷道支护技术

针对车集煤矿23下部采区复杂的围岩条件及原支护形式下的巷道破坏情况,对23下部采区轨道下山的地应力及围岩松动圈进行了测试,测试结果表明巷道水平应力大于垂直应力,地应力特征为水平应力场型,巷道围岩松动圈属于大松动圈软岩巷道。依据连续梁支护原理,采用大锚杆配合纵横向钢带交错联合支护方式,并强化了帮部的支护,实现了巷道围岩的整体控制,有效地防止了巷道的围岩变形,取得了较好的支护效果,为相似条件下的巷道支护提供一定的技术借鉴。

铁路车站路堑顺层边坡综合防护技术

以渝怀铁路铁碛坝车站路堑顺层边坡防护工程为例,介绍了应用预应力锚索抗滑桩、大锚杆结合钢筋混凝土骨架内喷播植草等多项措施,对顺层页岩边坡进行综合防护的施工过程作了论述,取得了良好的效果。

Anchoring effect and energy-absorbing support mechanism of large deformation bolt

To research the anchoring effect of large deformation bolt,tensile and drawing models are established.Then,the evolution laws of drawing force,bolt axial force and interfacial shear stress are analyzed.Additionally,the influence of structure element position on the anchoring effect of large deformation bolt is discussed.At last,the energy-absorbing support mechanism is discussed.Results show that during the drawing process of normal bolt,drawing force,bolt axial force and interfacial shear stress all gradually increase as increasing the drawing displacement,but when the large deformation bolt enters the structural deformation stage,these three values will keep stable;when the structure element of large deformation bolt approaches the drawing end,the fluctuation range of drawing force decreases,the distributions of bolt axial force and interfacial shear stress of anchorage section are steady and the increasing rate of interfacial shear stress decreases,which are advantageous for keeping the stress stability of the anchorage body.During the working process of large deformation bolt,the strain of bolt body is small,the working resistance is stable and the distributions of bolt axial force and interfacial shear stress are steady.When a rock burst event occurs,the bolt and bonding interface cannot easily break,which weakens the dynamic disaster degree.

Mechanism and technology study of collaborative support with long and short bolts in large-deformation roadways

Common short bolts of equal length are widely used to support the roofs of roadways in coal mines.However, they are insufficient to keep the roof stable against large deformations, so docking long bolts with high levels of elongation that can adapt to large deformations of the surrounding rock have been adopted. This paper proposes a collaborative support method that uses long and short bolts. In this study,the mechanism of docking long bolts and collaborative support was studied. Numerical simulation, similarity simulation, and field testing were used to analyze the distribution law of the displacement, stress,and plastic failure in the surrounding rock under different support schemes. Compared with the equal-length short bolt support, the collaborative support changed the maximum principal stress of the shallow roof from tensile stress to compressive stress, and the minimum principal stress of the roof significantly increased. The stress concentration degree of the anchorage zone clearly increased. The deformation of the roof and the two sides was greatly reduced, and the subsidence shape of the shallow roof changed from serrated to a smooth curve. The roof integrity was enhanced, and the roof moved down as a whole. Plastic failure significantly decreased, and the plastic zone of the roof was within the anchorage range. The similarity simulation results showed that, under the maximum mining stress,the roof collapsed with the equal-length short bolt support but remained stable with the collaborative support. The collaborative support method was successfully applied in the field and clearly improved the stability of the surrounding rock for a large deformation roadway.

Investigations into the corrosive environments contributing to premature failure of Australian coal mine rock bolts

University of New South Wales(UNSW Australia) had been involved in the study of premature failure of rock bolts in Australia coal mines from the initial identification of the problem in 1999. Rock bolt steel changes over the last decade appear to have not reduced the incidence of failures. A broadened UNSW research project funded by the Australian Research Council(ARC) and Industry has targeted finding the environmental causes through extensive field and laboratory experiments. This paper describes the field studies conducted in underground coal mines,in particular attempts to measure the contribution to corrosion from groundwater,mineralogy and microbial activity. Various underground survey techniques were used to determine the extent of broken bolts,with the presence of both stress corrosion cracking(SCC) and localized deep pitting making no single technique suitable on their own.Groundwater found dripping from bolts across various coalfields in Australia were found to be not aggressive and known groundwater corrosivity classification systems did not correlate to where broken bolts were found. In-hole coupon bolts placed in roof strata containing claystone bands confirmed the clay as being a major contributor to corrosion. Microbes capable of contributing to steel corrosion were found to be present in groundwater,and culturing of the microbes taken from in-situ coupon bolts proved that the bacteria was present on the bolt surface. An ‘in-hole bolt corrosion coupon' development by the project may have multiple benefits of (1) helping quantify newly developed corrosivity classification systems,(2) providing an in-situ ground support corrosion monitoring tool,and (3) for testing possible corrosion protection solutions.

Prediction of a maximum pull-out load of anchor bolts using an optimal combination model

The mixed model of improved exponential and power function and unequal interval gray GM(1,1)model have poor accuracy in predicting the maximum pull-out load of anchor bolts.An optimal combination model was derived using the optimally weighted combination theory and the minimum sum of logarithmic squared errors as the objective function.Two typical anchor bolt pull-out engineering cases were selected to compare the performance of the proposed model with those of existing ones.Results showed that the optimal combination model was suitable not only for the slow P-s curve but also for the steep P-s curve.Its accuracy and stable reliability,as well as its prediction capability classification,were better than those of the other prediction models.Therefore,the optimal combination model is an effective processing method for predicting the maximum pull-out load of anchor bolts according to measured data.

Effect of CO_2 enrichment on the glucosinolate contents under different nitrogen levels in bolting stem of Chinese kale (Brassica alboglabra L.)

The effects of CO2 enrichment on the growth and glueosinolate （GS） concentrations in the bolting stem of Chinese kale （Brassica alboglabra L.） treated with three nitrogen （N） concentrations （5, 10, and 20 mmol/L） were investigated. Height, stem thickness, and dry weights of the total aerial parts, bolting stems, and roots, as well as the root to shoot ratio, significantly increased as CO2 concentration was elevated from 350 to 800 μl/L at each N concentration. In the edible part of the bolting stem, 11 individual GSs were identified, including 7 aliphatic and 4 indolyl GSs. GS concentration was affected by the elevated CO2 concentration, N concentration, and CO2×N interaction. At 5 and 10 mmol N/L, the concentrations of aliphatic GSs and total GSs significantly increased, whereas those ofindolyl GSs were not affected, by elevated atmospheric CO2. However, at 20 mmol N/L, elevated CO2 had no significant effects on the concentrations of total GSs and total indolyl GSs, but the concentrations of total aliphatic GSs significantly increased. Moreover, the bolting stem carbon （C） content increased, whereas the N and sulfur （S） contents decreased under elevated CO2 concentration in the three N treatments, resulting in changes in the C/N and N/S ratios. Also the C/N ratio is not a reliable predictor of change of GS concentration, while the changes in N and S contents and the N/S ratio at the elevated CO2 concentration may influence the GS concentration in Chinese kale bolting stems. The results demonstrate that high nitrogen supply is beneficial for the growth of Chinese kale, but not for the GS concentration in bolting stems, under elevated CO2 condition.