合肥地铁创新大道站深基坑支护结构变形规律及优化

地铁基坑施工过程中支护结构应力变化和优化设计是施工的重点。通过对创新大道站地铁基坑进行数值模拟,得出了地表沉降和围护结构的受力及变形特性,并与监测数据进行对比,结果验证了模拟的正确性。基于数值模拟结果,对基坑支护结构进行优化,使其能够满足基坑设计安全和经济效益两个主要优化目标。优化后新方案的最大变形量仍能满足技术规范的要求。同时能够节约经济成本,缩短施工工期,具备一定的可实施性。     

湿陷性黄土中基坑支护的数值模拟分析

以河南省洛阳市某湿陷性黄土基坑工程为例,结合其所在区域的地质条件、周边环境等,采用了桩锚支护的基坑支护方案。针对该支护方案,应用有限差分程序FLAC3D建模分析了不同工况下支护结构和坑周土体的变形规律,得出了坑周土体的位移随着距坑距离的增大逐渐减小;支护桩的水平位移随着开挖深度的增加,桩顶处位移不断增大,而桩底部的位移越来越小;坑周地表沉降和水平位移及支护结构变形均满足设计要求。同时,研究了湿陷性黄土对桩土位移的影响,结果表明,该支护方案较为合理,桩锚支护结构对深基坑的变形起到了很好的控制作用。研究结果可为黄土地区湿陷性条件下的基坑支护技术及理论研究提供参考。     

预应力锚杆柔性支护在深基坑工程中的应用

预应力锚杆柔性支护技术广泛应用在深基坑工程中,为了研究其工作机理,对某一实际深基坑工程进行了数值模拟分析,并将预应力锚杆柔性支护和土钉支护两种方案进行了对比研究。分析结果表明:二维数值模型未考虑实际工程中基坑的空间效应,其数值计算结果偏安全;预应力在锚杆支护中起着重要作用,施加预应力可以明显减小基坑的变形;增加土钉长度或减小土钉间距,在一定程度上能减小基坑的变形,但很难控制基坑的整体稳定性;与土钉支护相比,预应力锚杆柔性支护可以有效控制基坑变形,从而保证基坑的整体稳定,能满足深基坑工程防护需求。     

万浩俪城S1工程深基坑支护方案设计与分析

万浩俪城S1工程东北边缘毗邻国家电网河东110 kV变电站,考虑到基坑周围环境的复杂性与支护工程的安全经济性,采取分段计算分析的方法,运用理正深基坑软件进行支护方案设计的计算.其中,Ⅰ段,基坑边缘距变电站2.0m,对土体变形敏感,空间狭窄无法放坡开挖,且土钉墙不能满足侧壁安全要求,选用桩锚支护结构;Ⅱ段周边为道路及开阔空地,采用放坡土钉墙支护结构.计算结果表明:桩锚支护段整体稳定性、抗倾覆、抗隆起等各项参数,放坡土钉墙支护段局部抗拉、内外部稳定性等参数,均满足规范要求,总体设计方案技术可行、合理经济.     

软土地基深基坑支护工程监测及变形特性分析

软土地基的复杂性及不定性是影响深基坑支护工程的重要因素.结合珠江三角洲某基坑地质条件较差的工程实例布置详细监测方案,并对基坑支护结构的水平位移、基坑地下水位、支撑轴力、基坑周边地表沉降的监测数据进行了综合分析,获得一些有价值的基坑变形规律.通过分析基坑支护结构及周边变形的因素,确保了基坑工程的施工质量以及周边建筑的安全.     

复合土钉支护在近接高速公路基坑工程中的应用

复合土钉支护结构可以减小基坑变形,防止紧邻道路、管线、建(构)筑物产生较大变形.给出土钉与锚杆、微型桩复合支护在近接高速公路基坑工程中应用实例,阐述该工程的设计、施工、监测技术要点.考虑高速公路汽车荷载计算了不同工况的基坑稳定安全系数,给出变形控制标准及控制措施.针对碎石和填土分层交替填筑、软硬不均地层,采用套管跟进进行钻孔,有效克服了卡钻现象.监测表明,基坑顶部高速公路路面最大水平位移控制在了10mm以内,满足控制标准的要求;锚杆支护是控制水平位移的有效措施.     

悬臂式基坑支护结构选型与整体稳定性分析

基坑工程是一项综合性很强的系统工程。结合基坑周边环境、开挖深度、工程地质与水文地质、施工作业设备和施工季节等条件,依据主体建筑结构设计、施工要求及建筑材料性能,对不同类型悬臂式基坑支护结构进行分析比较,在实际工程中合理选择出安全、经济、科学实用的基坑支护设计方案。全面地对基坑进行整体稳定性分析,是保证基坑工程安全的重要设计环节。工程实践证明,悬臂式基坑支护结构具有施工速度快、造价低、结构质量稳定和对变形有较好的控制能力等特点。     

渗透性土质下戴河大桥基坑支护分析

基于渗透性土层在渗流作用下的水土分算法原理,对戴河大桥桥墩基坑支护进行了设计与计算,运用有限元分析软件求得支护结构的变形值、基坑周围土体的沉降值等.在现场基坑开挖、降水过程中,合理设置监测点对支护变形及地表沉降实施了跟踪监测,将计算所得的支护最大变形值与实测最大变形值相比较,两者吻合较好,支护的强度、刚度、稳定性、抗管涌等性能满足建筑基坑工程检测技术规范的要求.     

基于FLAC3D的深基坑变形规律研究

为了分析深基坑开挖支护活动中应力应变连续变化过程对深基坑施工安全的影响,采用FLAC3D软件构建了深基坑有限元分析模型,通过分层开挖过程模拟,分析基坑各向变形规律,为支护方案的调整提供依据。模拟结果表明,基坑开挖至-3 m时,支护前后的Z向变形量分别为5. 89 mm和6. 03 mm,说明基坑隆起速率较高;基坑开挖至-7 m时,支护前后Z向变形量分别为11. 45 mm和11. 13 mm;基坑开挖至-12 m时,支护前后Z向变形量为12. 23 mm和12. 15 mm,X向变形量为12. 46 mm和12. 13 mm,Y向变形量分别为12. 45 mm和12. 11 mm。可见基坑坑底变形和侧向变形趋于稳定。深基坑各向变形指标均在合理范围内,说明采用分层开挖支护的方案是可行的。     

螺旋锚在基坑支护工程中的应用

根据株洲某基坑工程的地质条件、周边环境及基坑的设计深度,提出了螺旋锚支护方案,并对螺旋锚的抗拔承载力及支护结构进行了设计计算。计算结果表明:该支护方案对确保基坑稳定完全满足规范要求;同时,竣工后结算,采用螺旋锚支护方案与灌注桩方案的预算相比,节约了投资的50%,且不需进行砼养护,节省了工期。     

锚网索支架联合支护技术在深井巷道维修中的应用

针对河北金牛能源公司邢东煤矿深部轨道大巷失修严重的现实问题,对原锚网支护方式做了理论分析,提出锚网索支架联合支护维修的技术方案,并在力学机理分析基础上,对邢东矿深井锚网索支架联合支护技术进行了系统分析和应用研究。现场效果表明,锚网支架联合支护巷修技术是适用于邢东矿高应力条件的经济可靠的支护方式。     

高层建筑深基坑土锚支护结构体系的设计与施工

全面介绍了某市国贸大厦埋深１３．２,ｍ的三层地下室的深基坑选用的土锚支护结构体系的设计方案和施工工艺,并通过全面监测证明它具有较好的经济效益和社会效益。它是高层建筑深开挖施工的一种较好的支护结构体系。     

De-stressed mining of multi-seams: Surrounding rock control during the mining of a roadway in the overlying protected seam

Surrounding rock control in the overlying protective coal seam is a challenging topic for de-stressed mining of multi-seamed coal. Current research findings on roadway control were used in the design of a physical model of a complex textured roof having a varying thickness. The model was used to study roadway instability and collapse caused by dynamic pressure. The results show that when the thickness of the roof exceeds the bolted depth the roadway security is least and the roof has the greatest possibility for collapse. Numerical simulations were also carried out to study stress redistribution before and after roadway excavation during underlying protective seam mining. The evolution of roadway displacement and fracture, as affected by support methods, has been well studied. A series of support principles and technologies for mining affected roadways has been proposed after demonstration of successful practical application in the Huainan Mines. These principles and technologies are of extended value to deep coal mining support in China.     

Progress of heat-hazard treatment in deep mines

Based on the urgency of thermal hazard control in deep coal mines, we studied the status of deep thermal damage and cooling technology both at home and abroad, summarized the causes of deep thermal hazard, analysed and compared the control technologies for deep thermal hazards. The results show that the causes of deep thermal damage can be attributed to three aspects, i.e., climate, geological and mining factors, of which the geological factors are deemed the major reasons for thermal hazards. As well, we compared a number of cooling technologies of domestic and overseas provenance, such as central air conditioning cooling technology, ice cooling technology and water cooling technology, with one other cooling technology, i.e., the HEMS cooling technology, which has a large and important effect with its unique "pure air" cooling technology, realizes the utilizing of heat resources from underground to the ground. This technology makes use of heat obtained underground; thus the technology can promote low-carbon environmental economic development in coal mines, in order to achieve lowcarbon coal production in China.     

基于MathCAD的深基坑多点支护结构的设计计算

分析了深基坑支护结构的设计计算的方法 ,选择了在计算中考虑施工工况、计算结果与实际结果比较相符、在工程设计计算中广泛采用的分段等值梁法 ,结合MathCAD数学系统的优点 ,避免了在设计计算中需解高次方程、手工计算花很长时间的缺点 ,并通过工程实例验证了所采用的方法 ,为深基坑支护结构设计与施工提供快速合理的计算方法     

Influence of dynamic pressure on deep underground soft rock roadway support and its application

Due to high ground stress and mining disturbance, the deformation and failure of deep soft rock roadway is serious, and invalidation of the anchor net-anchor cable supporting structure occurs. The failure characteristics of roadways revealed with the help of the ground pressure monitoring. Theoretical analysis was adopted to analyze the influence of mining disturbance on stress distribution in surrounding rock,and the change of stress was also calculated. Considering the change of stress in surrounding rock of bottom extraction roadway, the displacement, plastic zone and distribution law of principal stress difference under different support schemes were studied by means of FLAC3D. The supporting scheme of U-shaped steel was proposed for bottom extraction roadway that underwent mining disturbance. We carried out a similarity model test to verify the effect of support in dynamic pressure. Monitoring results demonstrated the change rules of deformation and stress of surrounding rock in different supporting schemes. The supporting scheme of U-shaped steel had an effective control on deformation of surrounding rock. The scheme was successfully applied in underground engineering practice, and achieved good technical and economic benefits.     

Stability control of gate groups in deep wells

In order to study stability control methods for a deep gate group under complex stresses, we conducted field investiga-tions and analyses of reasons for damage in the Xuzhou mining district. Three reasons are proposed: deep high stress, improper roadway layout and support technology. The stability control countermeasures of the gate group consist of an intensive design technology and responding bolt-mesh-anchor truss support technology. Our research method has been applied at the -1000 m level gate group in Qishan Coal Mine. Suitable countermeasures have been tested by field monitoring.     

Stability influence factors analysis and construction of a deep beam anchorage structure in roadway roof

Deep beam anchorage structures based on spatial distribution analysis of the cable prestressed field have been proposed for roadway roof support. Stability and other factors that influence deep beam structures are studied in this paper using mechanical calculations, numerical analysis and field measurements. A mechanical model of deep beam structure subjected to multiple loading is established, including analysis of roof support in the return airway of S1203 working face in the Yuwu coal mine, China. The expression of maximum shear stress in the deep beam structure is deduced according to the stress superposition criterion. It is found that the primary factors affecting deep beam structure stability are deep beam thickness, cable pre-tension and cable spacing. The variation of maximum shear stress distribution and prestressed field diffusion effects according to various factors are analyzed using Matlabòand FLAC3D~(TM) software, and practical support parameters of the S1203 return airway roof are determined.According to the observations of rock pressure, there is no evidence of roof separation, and the maximum values of roof subsidence and convergence of wall rock are 72 and 48 mm, respectively. The results show that the proposed roof support design with a deep beam structure is feasible and achieves effective control of the roadway roof.     

深部沿空切顶成巷围岩稳定性控制对策

基于沿空切顶成巷技术原理,以城郊煤矿深部工作面无煤柱开采为背景,综合运用力学分析﹑模拟计算和现场试验等方法,对深部切顶成巷围岩控制关键对策进行深入研究。结果显示：切顶留巷顶板在侧向形成短臂梁结构,降低了巷旁支护体所受压力,切缝范围内岩层垮落后碎胀充填采空区,使留巷顶板下沉量降低了约50%。采空区侧顶板为切顶巷道围岩变形的关键部位,需进行加强支护;深部切顶巷道实体煤帮塑性区范围大,通过煤帮锚索支护技术可将浅部锚杆承载层锚固在弹性区稳定煤体中;深部切顶成巷来压速度快、强度大,巷内单体支柱易造成冲击破断,采用高阻力液压支架巷内临时支护时可较好地抵抗深部强动压;巷旁刚性挡矸装置因无法适应深部围岩大变形而受压弯曲破坏,深部切顶巷道巷旁挡矸结构需实现一定的竖向让位卸压方可与顶底板协调变形。在研究的基础上提出恒阻锚索关键部位支护+可缩性U型钢柔性让位挡矸+巷内液压支架临时支护+实体煤帮锚索补强的深部切顶成巷联合支护技术,并进行现场工业性试验。现场监测结果表明：留巷围岩在滞后工作面约290 m时基本稳定,且稳定后各项指标满足下一工作面使用要求。     

Double-directional control bolt support technology and engineering application at large span Y-type intersections in deep coal mines

Under deep and complex geological conditions,severe deformation occurs at intersection points of Y-type roadways with large cross sections during engineering projects in coal mines,especially at junction arches.Based on in-situ investigations and theoretical studies,we have summarized typical forms of destruction and identified high stress and unrestricted support at both sides of junction arch as its main causes.In this study,we also presented double-directional control bolt support technology for a large Y-type span intersection,applied to deep intersection engineering in the Jiahe Coal Mine,which has proved effective.