重大工程岩溶塌陷防治综合研究

重大工程选址时应尽量避开岩溶发育区,但受客观条件限制,很多工程仍不可避免地要布置在岩溶地区内,岩溶塌陷是工程建设可能遭受的主要地质灾害。新建昆明国际机场地质环境条件复杂,岩溶发育强烈,岩溶塌陷普遍存在,岩溶塌陷是新机场建设面临的最主要的工程地质问题。昆明新机场岩溶塌陷具有中国南方岩溶塌陷的典型特征,以昆明新机场为例开展岩溶塌陷防治综合研究,不仅对昆明新机场预防和治理岩溶塌陷具有指导作用,而且对其它岩溶地区重大工程的岩溶塌陷防治工作也有借鉴意义。本文是在充分收集、利用国内外岩溶塌陷方面的资料的基础上,结合昆明新机场实例开展岩溶塌陷综合防治研究的成果。(1)对新机场的地质环境进行了系统研究,对新机场水文气象、地形地貌、地层岩性、地质构造、水文地质、岩溶发育特征等进行了系统分析、归纳。(2)对新机场岩溶塌陷的形成条件和影响因素进行了系统分析、研究。运用MapGIS空间分析工具,将相关基础图件与岩溶塌陷分布图叠加后,对岩溶发育条件、盖层条件和致塌动力条件中的15个影响因素进行了详细分析、研究。工程区岩溶发育程度与塌陷频数具有一致的消长关系:D2h地层中岩溶塌陷最为发育;D3z地层中次发育;P1y、C2w、C1d2地层中较发育;∈2s地层中少量发育。一元结构的红粘土盖层土体中网状裂隙特别发育,最容易形成岩溶塌陷;工程区内松散层厚度越小,越容易产生岩溶塌陷,盖层厚度小于15m的塌陷占塌陷总数的94%。致塌动力条件包括大气降水、地表水、地下水、附加荷载和岩溶介质与大气联通情况等主要影响因素,其中大气降水的作用尤其突出。(3)按主导成因来划分,工程区岩溶塌陷类型包括降水下渗致塌、地下水位下降致塌和动荷载致塌降致塌三种类型。降水下渗致塌的机理是降水渗入松散盖层后,水流对盖层土体产生垂直渗透、饱和增重和吸水软化作用,在这些力的综合作用下导致松散盖层失稳直至垮塌。工程区内由地下水水位下降致塌的岩溶塌陷主要是由真空吸蚀作用和重力作用引起的;动荷载致塌,主要是由振动产生的破坏累计效应引起的。在系统分析、研究塌陷机理的基础上,分别建立了降水下渗致塌、地下水下降致塌机理下岩溶塌陷的稳定性评价力学模型。工程区内大部分岩溶塌陷的形成是多重原因复合叠加作用的结果,由单一原因引起的岩溶塌陷只是少数。工程区典型岩溶塌陷形成模式有地表水下渗和动荷载致塌模式、地下水下降致塌模式两种。(4)采用模糊层次综合法对工程区岩溶塌陷危险性进行预测评价。在系统分析主要岩溶塌陷影响因子的基础上,建立模糊层次评价模型,确定不同层次不同影响因子的权重;结合MapGIS空间分析工具,对含有不同权重的各致塌因子进行空间迭置分析计算,根据计算结果确定岩溶塌陷危险性等级并对工程区进行岩溶塌陷危险性分区,然后进行分区预测评价。所选方法适宜、可靠,预测结果可信。(5)建立了新机场岩溶塌陷数据库和信息系统,为新机场岩溶塌陷的系统分析、评价提供了资料翔实、手段先进的管理平台,使得机场建设和管理单位能够对岩溶塌陷资料进行便捷的查询和利用,具有较大的实际意义。(6)在充分总结、归纳国内外岩溶塌陷防治经验的基础上,选择具有代表性的试验区,开展了岩溶塌陷防治工程试验研究。针对岩溶塌陷的形成条件和影响因素,选取处置对象和试验方法,试验针对隐伏溶洞和红粘土盖层分别进行,隐伏溶洞的处理采用混凝土+袖阀注浆法;红粘土采用垫层强夯法和碎石桩法进行处理。试验后采用多种检测手段进行检测、验证。试验方法正确、适宜,检测手段客观、可靠,防治效果明显。(7)根据工程区防治试验成果和国内外岩溶塌陷工程防治经验,提出了工程区岩溶塌陷防治处置对象及方法建议,分功能区分别提出了岩溶塌陷防治方案建议。将采取工程防治措施后影响因子的改善情况重新取值,然后取办公区和西飞行区对岩溶塌陷危险性重新进行计算、预测,将采取工程措施前、后的结果进行比较,认为工程防治方案适宜、可行,效果比较明显。(8)将系统科学和运筹学理论运用于岩溶塌陷工程防治决策中,对岩溶塌陷防治工程决策模式和方法等进行了探索性研究,对于地质灾害的防治与管理具有较重要的意义。根据决策学理论结合本项工程实际情况,提出了昆明新机场岩溶塌陷防治工程决策模式为:确定目标→收集信息→确定决策判据→制定防治方案→对各种方案的决策判据分析、计算→选择决策方法→决策:选择最优方案。结合工程实际,选择乘除法、功效系数法、线性加权和法、层次分析法分别进行决策计算,采用综合决策法确定了办公区和西飞行区防治方案。决策方法较客观、合理,为新机场科学防治岩溶塌陷决策提供了依据。论文在系统分析、论述工程区岩溶塌陷成因、机理的基础上,以岩溶塌陷形成条件和影响因素为中心,对工程区岩溶塌陷防治进行了综合研究并提出了工程防治建议。论文成果达到了预期目标,不仅能为昆明新机场建设起到一定指导作用,而且对其它类似重大工程的岩溶塌陷防治工作也有借鉴意义 毛毡杯垫饰品挂件
When important project selected location should avoid the karst growth area as far as possible, but receives the detachment condition limit, many projects still inevitably must arrange in the karst area, the karst collapse is the main geological disaster which the engineering construction possibly suffers. The newly built Kunming international airport geological environment condition is complex, the karst growth is intense, karst collapse universally exist, The karst collapse is the most main engineering geological question which the new airport construction faces. The Kunming New Airport karst collapse has south China the karst collapse typical characteristic, take the Kunming New Airport as example development karst collapse prevention synthetic study, not only has the instruction function to the Kunming New Airport prevention and the government karst collapse, moreover also has to other karst area important project’s karst collapse prevention profits from the significance. This article is in the full collection, uses the domestic and foreign karst collapse aspect in the material foundation, unifies the Kunming New Airport example development karst collapse integrated control research the achievement.(1) Has conducted the system research to the new airport’s geological environment, to the new airport hydrometeorology, the terrain landform, the formation lithology, the geologic structure, the hydrology geology, the karst growth characteristic and so on has carried on the system analysis, the induction.(2) Have carried on the system analysis, the research to the new airport karst collapse’s formation condition and the influencing factor. Using the MapGIS spatial analysis tool, after will be related the foundation graphic document and the karst collapse distribution map superimposition, to the karst condition of development, the cap rock condition and sends collapses in the dynamic condition 15 influencing factor to carry on the multianalysis, the research.. The project area karst growth degree has the consistent increase and decrease relations with the collapse frequency: In the D2h stratum the karst collapse most grows; Next,in the D3z stratum growth; Then, in the P1y, C2w, C1d2 stratum grows;∈2s in stratum few growth.. In a Yuan structure’s red clay coating soil body the netted crevasse grows specially, easiest to form the karst collapse; In the project area loose level thickness is smaller, easier to have the karst collapse, the depth of cover is smaller than the 15m collapse accounts for the collapse total 94%. Sends collapses the dynamic condition including the mospheric water, the surface water, the ground water, the ditional load and the karst medium and the atmospheric link situation and so on major effect factor, mospheric water’s function is especially prominent.(3) Divides according to the leading origin, the project area karst collapse type infiltrates including the precipitation under sends collapses, the groundwater level to drop sends collapses and moves the load to send collapses falls sends collapses three types. Under after the precipitation infiltrates the mechanism which sends collapses is the precipitation permeates the loose cap rock, the current of water to the cap rock soil body has the vertical seepage, saturated to increase heavy and the absorbing water ramollescence, causes the loose cap rock jitter under these strength’s combined action until collapsing. In the project area drops the karst collapse which by the phreatic water surface sends collapses is mainly by the real suction eclipse function and the action of gravity causes; Moves the load to send collapses, is mainly the destruction accumulation effect which produces by the vibration causes. In the system analysis, in the research collapse mechanism’s foundation, established under the precipitation to infiltrate separately sends collapses, the ground water to drop sends collapses under the mechanism the karst collapse stable appraisal mechanical model. In the project area the majority of karst collapse’s formation is the multiple reason compound superimposition function result, causes the karst collapse by the sole reason is only minority. The project area typical karst collapse forms the pattern to have under the surface water to infiltrate and to move the load to send collapses the pattern, the ground water to drop sends collapses the pattern two kinds.(4) Uses the fuzzy level synthesis method to carry on the forecast appraisal to the project area karst collapse risk. In the system analysis main karst collapse influence factor’s foundation, establishes the fuzzy level evaluation model, the determination different level different influence factor weight; Unifies the MapGIS spatial analysis tool, to includes the different weight to send respectively collapses the factor to carry on the spatial repeat to set at the analysis computation, according to the computed result determined that the karst collapse risky rank and carries on the karst collapse risky district to the project area, then carries on the district forecast appraisal. Chooses method being suitable, reliably, the forecasting result is credible.(5) Has established the new airport karst collapse database and the information system, for the new airport karst collapse’s system analysis, the appraisal provided the material to be full and accurate, the method advanced management platform, caused the airport construction and the Administrative unit can carry on the convenient inquiry and the use to the karst collapse material, had the big practical significance.(6) In the full summary, induces in the domestic and foreign karst collapse prevention experience’s foundation, the choice has the representative pilot area, has carried out the karst collapse prevention engineering test research. In view of karst collapse’s formation condition and the influencing factor, the selection handling object and the testing method, experiments in view of the underlying limestone cave and the red clay coating carries on separately, underlying limestone cave’s processing uses the concretes + sleeve valve note thick liquid law; The red clay uses the breaker strip strong hang law and the broken stone marker law carries on processing. After the experiment, uses many kinds of examination methods to carry on the examination, the confirmation. The testing method is correct, being suitable, the examination method is objective, is reliable, the control efficiency is obvious.(7)According to the project area prevention experiment achievement and the domestic and foreign karst collapse project prevention experience, proposed the project area karst collapse prevention handling object and the method suggested that the division of work energy region put forward the karst collapse prevention plan proposal separately. After will take the project prevention measure, affects the factor the improvement situation again value, then takes the office district and west the flight area carries on the computation, the forecast to the karst collapse risk, will adopt the mechanical control measure before and after result to carry on the comparison, thought that project prevention plan being suitable, feasible, the effect is quite obvious.(8)Utilize the systems science and the operations research theory in the karst collapse project prevention decision-making, and so on has conducted the exploring research to the karst collapse prevention project decision model and the method, has the vital significance regarding the geological disaster’s prevention and the management. Unifies this project actual situation according to the decision-making study theory, proposed the Kunming New Airport karst collapse prevention project decision model is: Definite goal -> collection information -> determination decision-making criterion -> formulation prevention plan -> to each kind of plan policy-making criterion analysis, computation -> choice decision method -> decision-making: Choice synergy. The union project reality, chooses while the division, the effect method of correlates, the linear weighted sum law, the analytic hierarchy process carries on the policy-making computation separately, used the compound decision law to determine the office district and west the flight area prevention plan. The decision method is objective, reasonably, has provided the basis for the new airport science prevention karst collapse decision-making.The paper in the system analysis, the elaboration project area karst collapse origin, in mechanism’s foundation, forms the condition and the influencing factor take the karst collapse as a center, has conducted the synthetic study to the project area karst collapse prevention and put forward the project prevention proposal. The paper achievement has achieved the anticipated target, not can only construct certain instruction function for the Kunming New Airport, moreover also has to other similar important project’s karst collapse prevention profits from the significance