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1.
西部地区主要为白垩系软岩地层, 煤炭资源储量大, 成为我国重要产煤区. 白垩系软岩地层冻结壁温度场分布规律尚不清楚, 给白垩系地层冻结法凿井设计与施工带了一定的困难. 通过现场实测、室内试验和数值模拟等手段, 获得了白垩系地层冻结软岩热物理参数分布规律、力学特性及深井冻结壁冻融规律. 测点冻结温度场反演白垩系冻结软岩导热系数值一般介于3.328~3.465 W·m -1·K -1之间, 现场实测表明: 白垩系地层融冻时间比一般为1.0~1.2之间. 研究白垩系地层冻融规律, 对指导我国西部地区白垩系地层冻结法凿井设计与施工具有重要的理论参考价值. 相似文献
2.
深厚冲积层冻结压力取值大小是冻结法凿井外层井壁设计计算的重要依据。为此,基于符合深井冻土蠕变特性的改进西原模型,利用ABAQUS软件的用户子程序接口,实现该模型的UMAT开发。考虑土体冻结过程中的热-力耦合作用获得井筒开挖前土体冻胀应力分布规律,在此基础上,计算分析了深部冻结井的掘砌过程,获得了作用于外层井壁的冻结压力发展变化规律。计算结果表明：土体埋深、冻结壁温度、土体冻胀率等因素均影响冻结压力的大小。在其他条件不变的情况下,当埋深由400 m增加到500 m时,冻结压力增加21%;当冻结壁平均温度由-16 ℃降低至-18 ℃时,冻结压力减小10%;当土体冻胀率由2%增加到3%时,冻结压力增加3.8%。冻结压力随层位深度及土体冻胀率的增加而增加,而降低冻结壁温度则有利于冻结壁的稳定。数值计算结果与实测值的误差小于15%,比理论计算更有利于实际工程中深井冻结压力的计算预测。 相似文献
3.
As a clean form of energy able to replace oil, the demand for LNG (Liquefied Natural Gas) has been increasing. LNG must be stored in a cryogenic temperature of —162°C. The storage tanks now existing throughout the world can be divided into above-ground and inground types. In the Tokyo area, there are now 22 in-ground LNG storage tanks, either in operation or under construction, which are constructed with primary consideration given to safety and earthquake-proof design because of the circumstances around the LNG terminals. In the feasibility study of a very large-scale, in-ground LNG storage tank, comparative preliminary studies were made of various construction methods. Among them, the method using artificial ground freezing was proposed, in which it was planned to utilize the frozen soil as the means of ground water control and the temporary retaining wall. To confirm the feasibility of the design, a model tank test was conducted by freezing the actual tank yard. The yard ground, composed of sand and silt layers, was artificially frozen 10 m in diameter and 50 m in depth; in the frozen soil a shaft of 4 m in diameter was sunk to a depth 26 m below the ground level for various tests and measurements. The purpose of the test was mainly to confirm the construction method and to examine the agreement between theory and practice. Although this construction method has not been adopted in the actual tank work, the feasibility of the method itself has been confirmed as a result of the test. In this paper, the outline and major results of the test and analysis are described. 相似文献
4.
西部煤矿冻结建井穿越岩层以白垩系、侏罗系等富水弱胶结地层为主,在温度场和地应力场的耦合作用下冻结壁岩体经历了一次完整的冻融过程。以白垩系富水弱胶结红砂岩为研究对象,充分考虑红砂岩冻融过程中受到的温度场与地应力场耦合作用环境,基于力学试验得到白垩系弱胶结红砂岩冻结融化后的力学性质及冻融过程中的地应力对红砂岩力学参数的影响,对白垩系弱胶结红砂岩冻融劣化机理及冻融过程中地应力的影响机制进行了分析。冻融过程中围压分别设置为0、2、4、6、8 MPa,冻结温度分别设置为?5、?10、?15 ℃,融化温度统一设置为20 ℃。试验结果表明,白垩系弱胶结红砂岩胶结差、强度低,对冻融作用非常敏感,仅经历一次冻融后单轴抗压强度即下降28.39 %;冻融过程中的地应力提高了白垩系弱胶结红砂岩孔隙裂隙的约束能力,使冻结作用可以尽可能地向次级微孔隙发展,随着冻结程度的加深,红砂岩内部冻胀力进一步增加,损伤加剧,故而融化后的力学参数相对于无围压冻融进一步降低。研究结果为西部地区煤矿冻结建井井壁设计提供了指导。 相似文献
5.
提出了国内广泛采用的悬浮下沉井壁钻井施工法有其深度极限的观点。分析了泥浆中的井壁筒在加入配重水（非满水）后井壁底接触岩石时的受力状态;结合国内悬浮下沉井壁钻井法的工艺特点,建立了泥浆中的井壁筒为有底管状自重压杆的力学模型;以能量法为基础,利用结构稳定理论和流体力学理论原理,推导了非满配重水井壁筒竖向结构稳定临界高度的解析式,并给出了典型算例;强调了工程设计中利用该公式的注意事项,并指出进一步研究这一问题的内容和方法。 相似文献
6.
针对冻土受力变形的特性，给出了白光散斑照相，激光散射照相和激光显微散照相技术相结合测量冻土位移的方法，分析讨论了各种散斑照相的测量范围，对冻土弹性变形范围内的位移测量实验表明，这是一种有效的测量手段。 相似文献
7.
At present,artificial freezing method has become one of the effective methods for coal mine shaft to pass through water-rich soft rock strata,which can stop the movement of groundwater and limit the deformation of surrounding rock. In order to study the frost heaving characteristics of sandstone under different freezing conditions,frost heaving tests of saturated and dry Cretaceous red sandstone samples under different freezing rates （10 ℃·h-1,5 ℃·h-1,2 ℃·h-1,1 ℃·h-1）and different confining pressures（5 MPa,10 MPa,15 MPa,20 MPa,25 MPa）were carried out by using GCTS（Geotechnical Consulting & Testing Systems）servo-controlled low temperature and high pressure triaxial rock testing system. In this paper,based on the existing theory of physical and mechanical properties of frozen soil,we studied the frost heaving law of sandstone under different freezing conditions and explored the frost heaving mechanism. The result shows that in the process of cooling,the dry rock sample always produce cold shrinkage deformation,while the saturated rock sample first produce cold shrinkage deformation,then produce frost deformation,and finally the deformation tends to be stable. The deformation of saturated rock samples is much larger than that of dry rock samples. The larger the stress level of rock samples at the same temperature is,the smaller the frost deformation is,which shows a linear negative correlation,mainly because the high confining pressure limits the volume expansion of the water phase in the pore inside the rock samples when it becomes ice. The frost deformation of rock samples is mainly affected by confining pressure and water content,while the frost heaving rate is mainly affected by cooling rate. Under this test condition,the higher the cooling rate of sandstone is,the higher the frost heaving rate is,and the relationship between them is approximately linear. For saturated rock samples,the confining pressure reduces the rock frost heaving by limiting the expansion during the phase transformation of ice water,and the temperature affects the rock frost heaving by affecting the freezing rate of pore water and the thermal expansion and cold contraction of rock skeleton. For dry rock samples,the deformation is mainly due to the volume contraction of rock mineral particles caused by thermal expansion and cold contraction effect,and the greater the temperature change,the greater the deformation. Based on the experimental results and theoretical analysis method,a calculation formula of rock frost heaving considering the influence of confining pressure was established. By calculating the frost heave of sandstone samples under different confining pressures,it is found that the calculated values are in good agreement with the experimental results. Moreover,according to the calculation formula of frost heaving,the influence factors of rock frost heaving during freezing can be divided into two categories：internal cause and external cause. The internal cause includes porosity,saturation,volume modulus of ice and rock skeleton,and the external cause includes temperature and confining pressure. For saturated rock,the frost heaving is mainly affected by factors such as confining pressure,temperature and porosity. When the saturation,porosity and freezing rate are low,the rock may only produce shrinkage deformation,because these indicators determine whether the rock produces frost heave or freeze shrinkage. The mechanism of rock frost heaving is very complicated due to the interaction and restriction between the internal and external factors and the dynamic changes of rock micro-structure and mechanical properties during the process of frost heaving. The research results can provide theoretical reference for freezing construction scheme design of deep coal seam mine construction,and also provide a theoretical basis for the study of physical and mechanical properties and engineering application of soft rock in frozen soil area. © 2022 Science Press (China). 相似文献
9.
Freezing was used in the jointing section of two shields (diameter 3.14 m) which ran across at right angles and at 25-m depth under the crossing of main roads for the construction of a 2.4-m diameter sewer tunnel. The object of freezing was to create a frozen barrier to prevent the inflow of water and fine sand into the area to be excavated. Thirty-five freeze pipes (length about 7 m) were placed from one shield conically in the direction of the flank of another shield with freeze pipes attached to its inside wall. The cooling unit was placed on unoccupied land at about 60 m distant from the jointing section and the freeze pipes were connected with the cooling unit by supply and return pipelines. The cooling unit had a cooling capacity of 79,000 kcal/h at an evaporation temperature of −27°C and a condensation temperature of +40°C. Freezing was continued for 180 days and the CaCl2 brine temperature was −25 to −30°C. These works were accomplished without the sinking of shaft and the use of injection, in complete safety with no traffic restriction on the road surface. 相似文献
10.
新庄煤矿立井采用冻结法施工技术,在井筒开挖的过程中,由于侧向卸荷作用导致围岩产生卸荷变形。从新庄煤矿立井现场采集白垩系中粒砂岩,对加工后的岩样进行饱水处理,然后利用GCTS电液伺服控制高低温高压岩石三轴测试系统进行冻结（-10 ℃）条件下的恒轴压、卸围压三轴试验,模拟在井筒开挖过程中围岩的应力变化路径,探索冻结砂岩的变形特性。研究表明：侧向卸荷条件下冻结砂岩表现出弹-脆性特征,轴向表现为压缩变形,径向表现为膨胀变形,径向变形量约为轴向变形量的2倍;当卸荷速率一定时,岩样的卸荷变形随初始围压的增大而增大,尤其是径向变形最为显著,这可能与卸荷回弹变形及岩样内部聚集的能量大小有关;围压卸荷到同一应力水平时,高卸荷速率下岩样的卸荷变形量较小,而变形速率较大;卸荷作用导致岩样变形模量减小,横向应变与纵向应变之比增大,卸荷速率越小,初始围压越大,应变之比变化越大。 相似文献
11.
山东单县煤田陈蛮庄煤矿松散层厚度为527.5m,预注浆段井深为750.-758.40m,预计涌水量为26m^3/h,为有效治理工作面水害,确保井筒的安全施工和进度质量,根据基岩段围岩条件及水文地质条件设计了10个预注浆孔,注浆段混凝土材料由C40变为C70,确定含水层预注浆的止浆垫厚度为10m,预留岩帽厚度为4.5m。在注浆时采取高压分段注浆的方法,结果使主井涌水量减少到2.4m^3/h,效果显著。通过此次注浆,总结出了＂探、注、堵＂等一套深立井基岩含水层综合注浆堵水施工技术,对深立井井筒工作面探水预注浆和安全施工具有借鉴意义。 相似文献
12.
通过深部高承压水地层冻结法凿井现场实测,获得矿井裂隙岩体各个层位测温孔的温度和盐水去回路干管温度变化规律.结果表明:测温孔实测温度在冻结初期呈线性下降规律;当温度继续降低到岩石的结冰温度以后,降温速率逐步增加;当冻结帷幕达到设计温度时,实测温度变化趋于平缓;外圈管外侧测温孔降温速率最慢,两圈管之间位置的测温孔降温速率最快;位于不同位置不同层位的测温孔降温速率不一致,其中位于92m深度的卵石层(C1 #测温孔)降温速率为0.54℃·d -1,位于209m深度的砂质泥岩(C3 #测温孔)降温速率为0.9℃·d -1;根据实测温度可以预测地层形成冻结帷幕的交圈时间、厚度、平均温度等冻结设计参数.深部裂隙岩体冻结温度实测资料对指导冻结帷幕设计与施工具有重要实践意义. 相似文献
13.
The Boom clay is considered as a candidate host rock for the Belgian disposal of radioactive waste. Thanks to the recent sinking
of a new shaft to extend the Underground Research Laboratory (URL) at the Mol site, new in-situ data have been obtained. They
consist in the observation of significant fracturing, evidenced during the excavation of the shaft annexes, and in correlated
hydraulic perturbations in the far field (maximum of 0.2 MPa at 60-m radius). These observations cannot be explained from
simple poroplastic models that predict a maximum perturbation extent of 25 m under full deconfinement. Thus, models with increasing
complexity are built to explain this discrepancy. It is proposed that the low-support pressure imposed by the primary lining,
combined with the long time over which this support condition held, has favoured the decompression of the clay massif through
time-dependent effects, mainly skeleton viscosity. This resulted in near-field fracturing, leading to an apparent increase
of the excavated radius and to a hydraulic perturbation in the far field. This interpretation still needs to be validated/invalidated
with future research. The effect on the overall performance of the repository is expected to remain small due to the self-healing
nature of the fractures.
Electronic Publication 相似文献
14.
以安徽祁南矿东风井冻结法凿井为工程背景,以多圈管冻结的不同土性表土层为研究对象,基于冻结孔实际成孔位置,应用有限元软件COMSOL Multiphysics分别建立埋深218 m钙质黏土层位、埋深225 m细砂层位和埋深259 m砂质黏土层位3个不同土性、不同埋深的冻结温度场数值计算模型,并结合现场实测数据,分层计算分析了其冻结壁温度场时空演化规律,结果表明:在相同冻结条件下,埋深225 m细砂层位冻结壁有效平均温度比埋深259 m砂质黏土层位和埋深218 m钙质黏土层位分别低0.09~0.72℃和0.44~1.95℃,埋深225 m细砂层位平均有效厚度比埋深259 m砂质黏土层位和埋深218 m钙质黏土层位分别厚0.17~0.38 m和0.29~0.47 m;现场实测与数值计算均表明,各个层位冻结壁开挖时,其平均温度均低于–15℃,有效厚度均大于6.2 m,200 m以下深部表土层井帮温度低于–4℃,满足施工要求,冻结壁强度和稳定性均处于安全状态;冻结孔沿径向将冻结温度场划分为3个区域(A区、B区、C区),B区在冻结孔冷量叠加的影响下降温速度最快,A区降温速度适中,C区距离冻结管较远,且外部土体源源不断向其输入热源,降温速度最慢。该研究可为冻结法凿井中冻结壁的施工提供一定的理论参考。 相似文献
15.
在试验研究的基础上,探讨了饱水砂层的竖向冻结及融化过程土中结构切向受力的变化．试验结果表明,冻结饱和砂土融化过程可分为负温升温、相变和自由水温升３个阶段;与此对应,融化沉降过程可分为开始、急降和缓降３个阶段;而模型结构切向应力则经历了上升、陡降和缓降３个过程;最终模型受有切向融沉压缩附加应力．这对于进一步研究季节性冻土中的结构受力、冻结井井壁应力历史以及井壁裂漏颇有意义． 相似文献
16.
通过模拟人工冻结凿井中冻土冻结、受力的实际过程,对已冻结试样进行不同温度、不同初始围压状态下的减载试验研究.结果表明:温度和土层深度是影响深部冻土破坏强度和破坏应变的主要因素,当温度不变时,破坏强度和破坏应变随初始围压呈线性关系变化.破坏强度受温度的影响取决于初始围压,在低初始围压状态下,冻土的破坏强度受温度变化影响不明显,但随着初始围压增大即土层深度加深,破坏强度受温度的影响也逐渐明显.破坏应变随温度的降低而逐渐减小,且呈双曲线形变化,但当温度低于 - 7℃时,在不同初始围压下其破坏应变基本不随温度的变化而变化 相似文献
17.
多圈管冻结工法已在深厚地层井筒掘砌中广泛应用,但对多圈管冻结温度场需进一步深入研究。以某冻结井筒为原型,对关键层位开展冻结管无偏斜条件下的冻结温度场模型试验、进行冻结管偏斜条件下的温度场数值计算,同时利用温度场信息可视化软件对现场实测结果进行分析。将三种测试手段获得的结果进行比较,得出冻结管偏斜对冻结壁有效厚度影响较小,但对冻结壁平均温度、冻结壁交圈时间影响都很大,且容易在冻结壁内部产生密闭未冻承压水仓,造成冻胀力聚集,对冻结壁整体稳定性及井筒开挖不利。其结果可为多圈管冻结法凿井设计与施工提供参考。 相似文献
19.
Tensile fracture is an ubiquitous feature of rock failure ranging in size from microfracture around Griffith cracks to the large-scale explosive failure accompanying rock bursts in underground cavities. Hence the resistance of rock to failure in tension, the tensile strength, is one of the fundamental parameters of rock strength. The tensile strength of rock is, however, a most elusive parameter which is difficult to measure and to define. The tensile strength, and its variation with direction, was determined by the pointloading and the line-loading (Brazilian test) methods for nine rocks from five sandstone formations in New Brunswick, Canada. Altogether 319 double point-load and 357 line-load tests were conducted on discs having a diameter of 22.9 mm and thickness of 7.9 mm. The tensile strength determined by the point-load test and as calculated by the Frocht formula was found to be consistently lower than that obtained by the line-loading technique. To some extent, the difference is due to the fact that most of the sandstones are anisotropic with respect to tensile strength and that the constraints in the point-load test are such that fracture occurs along the plane of minimum tensile strength; the computed tensile strength therefore represents a minimum value. To a greater extent, the lower tensile strength calculated from the point-load test is due to the difference in the states of stress induced by the two techniques. When correction is made for the anisotropy, the tensile strength from the Brazilian test is still 3.76 times larger than the one obtained from the point-load test. The Brazilian test seems to yield a more accurate definition of both the tensile strength and its variation with direction. The point-load test is more suitable for the determination of the minimum value of tensile strength and the direction of the preferred fracture plane. 相似文献
20.
安徽琅琊山抽水蓄能电站调压竖井井深70 m,外径20 m,内径18.6 m。利用吊盘、吊笼、卷扬机建立灌浆提升系统,完成井身段固结灌浆。通过优化施工方案、合理组织施工、建立完善的规章制度、加强职工职业培训、严格执行施工安全技术措施,圆满地完成了灌浆施工任务。 相似文献
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