Study on strata control by delay grouting in soft rock roadway

The properties of broken rock before and after grouting reinforcement are studied. Testing results show that grouting can raise the residual strength of broken rock, and the broken rockness by grouting can keep the steady supporting capacity within a relatively large deformation range. Revealing of the characteristics of stage deformation and damage process comes to the conclusion that the supporting of soft rock roadway should be analyzed in a dynamic view, and the grouting should be delayed at a proper occasion. Based on the above, the stepwise reinforcement technology characterized by immediate shotcreting, timely bolting and delay grouting is put forward and illustrated with a successful engineering practice.

The research progress and prospect for the technology of controlling surface subsidence by grouting separated layer in overburden at coal mines in China

The developed process and theoretical achievement for the technology of controlling surface subsidence by grouting separated layer in overburden is summarized in this paper. The research progress of the technology is discussed synthetically on the basis of practice and research results obtained at coal mine of China in recent years. According to the development tendency of mining under buildings, water bodies and railroads and the properties of the technology, the future research direction is proposed.

Mechanical Behaviors and Deformation Properties of Retaining Wall Formed by Grouting Mould-Bag Pile

The simplified mechanical model and finite element model are established on the basis of the measured results and analysis of the grouting pile deformation monitoring,surface horizontal displacement and vertical displacement monitoring,deep horizontal displacement(inclinometer)monitoring,soil pressure monitoring and seepage pressure monitoring in the lower reaches of Wuan River regulation project in Shishi,Fujian Province.The mechanical behavior and deformation performance of mould-bag pile retaining wall formed after controlled cement grouting in the silty stratum of the test section are analyzed and compared.The results show that the use of controlled cement grouting mould-bag pile technology is to strengthen the soft stratum for sealing water and reinforcement,so that it can rock into a retaining wall,which can both retain soil and seal water with excellent effect.The control of cement grouting technology not only makes the soft soil rock in the range of retaining wall of mould-bag pile,but also makes a wide range of soil around the mould-bag pile squeeze and embed to compaction;and its cohesion and internal friction angle increased,so as to achieve the purpose of reducing soil pressure and improving mechanical and deformation properties of retaining wall.

Development of the nano-composite cement:Application in regulating grouting in complex ground conditions

Improvement of the fluidity and setting time of grouting materials has been recognized as an effective approach of seepage prevention in foundation works, and it is quite common to be used for handling severe leakages in complex ground conditions, such as loose, broken and fully fissured stratum. For the purposed of better meeting the engineering requirements, experimental studies were conducted in this study with focus on the nanocomposite grouting materials and the related controlled grouting technology. As compared with the commonly used silicate-sulpho-aluminate composite cement, which is characterized by relatively poor rheological property, quick setting time and low strength, the most suitable nano-material with proper reactants were selected intentionally to improve the mentioned attributes of composite cement. Due to the setting time and strength of the targeted cement slurry behaving with poor performance of harmonization to engineering construction problems, hydration synergistic effect of these composites were investigated in our experiments. Results showed that the properties of grouting materials, including initial fluidity, setting time, ideal right-angle thickening, and early strength and late strength were sufficient to produce an expected grouting application. It is therefore advocated that the refined grouting material could provide a better solution to fix grouting problems in complex ground cementing operations.

Deformation of mining caving zone grouting compound rock under overlying strata pressure

To solve the problem of surface subsidence caused by mining,the main method is to reasonably process coal mining space.'Mining caving zone high-pressure grouting pulverized coal ash hydromass controlling roof and overlying strata movement' technology is one of processing methods.After grouting pulverized coal ash hydromass in mining caving zone,formed one kind of special material which is used to support roof and effec- tively control the subsidence of overlying strata.For the accurate calculation of roof mining subsidence at grouting state,based on the characteristics of such materials,established its constitutive equation based on certain assumptions,gave deformation calculation method when the compound rock supports overlying strata,lay foundation for the actual calculation of subsidence of overlying strata after grouting and the promotion of mining caving zone grouting technology.

Seismic performance of fabricated continuous girder bridge with grouting sleeve-prestressed tendon composite connections

The seismic performance of a fully fabricated bridge is a key factor limiting its application.In this study,a fiber element model of a fabricated concrete pier with grouting sleeve-prestressed tendon composite connections was built and verified.A numerical analysis of three types of continuous girder bridges was conducted with different piers:a cast-in-place reinforced concrete pier,a grouting sleeve-fabricated pier,and a grouting sleeve-prestressed tendon composite fabricated pier.Furthermore,the seismic performance of the composite fabricated pier was investigated.The results show that the OpenSees fiber element model can successfully simulate the hysteresis behavior and failure mode of the grouted sleeve-fabricated pier.Under traditional non-near-fault ground motions,the pier top displacements of the grouting sleeve-fabricated pier and the composite fabricated pier were less than those of the cast-in-place reinforced concrete pier.The composite fabricated pier had a good self-centering capability.In addition,the plastic hinge zones of the grouting sleeve-fabricated pier and the composite fabricated pier shifted to the joint seam and upper edge of the grouting sleeve,respectively.The composite fabricated pier with optimal design parameters has good seismic performance and can be applied in high-intensity seismic areas;however,the influence of pile-soil interaction on its seismic performance should not be ignored.

Theory,technology and application of grouted bolting in soft rock roadways of deep coal mines

The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured roadways.It has been extensively applied in numerous deep mining areas characterized by soft rock roadways,where it has demonstrated remarkable control results.This article systematically explores the evolution of grouted bolting,covering its theoretical foundations,design methods,materials,construction processes,monitoring measures,and methods for assessing its effectiveness.The overview encompassed several key elements,delving into anchoring theory and grouting reinforcement theory.The new principle of high pretensioned high-pressure splitting grouted bolting collaborative active control is introduced.A fresh method for dynamic information design is also highlighted.The discussion touches on both conventional grouting rock bolts and cable bolts,as well as innovative grouted rock bolts and cables characterized by their high pretension,strength,and sealing hole pressure.An examination of the merits and demerits of standard inorganic and organic grouting materials versus the new inorganic–organic composite materials,including their specific application conditions,was conducted.Additionally,the article presents various methods and instruments to assess the support effect of grouting rock bolts,cable bolts,and grouting reinforcement.Furthermore,it provides a foundation for understanding the factors influencing decisions on grouted bolting timing,the sequence of grouting,the pressure applied,the volume of grout used,and the strategic arrangement of grouted rock bolts and cable bolts.The application of the high pretensioned high-pressure splitting grouted bolting collaborative control technology in a typical kilometer-deep soft rock mine in China—the soft coal seam and soft rock roadway in the Kouzidong coal mine,Huainan coal mining area,was introduced.Finally,the existing problems in grouted bolting control technology for deep soft rock roadways are analyzed,and the future development trend of grouted bolting control technology is anticipated.

Failure mechanism and stability control technology of rock surrounding a roadway in complex stress conditions

To solve the problem of supporting three downhill coal structures in the Yongan Coal Mine of Shanxi Jincheng, we studied the regular development of stress and plastic zones and characteristics of deformation of rock surrounding roadway groups after a period of roadway driving, mining one side as well as mining both sides, we used FLAC 3D for our numerical and theoretical analyses. Field test were carried out, where we revealed the deformation mechanism of roadways and its coal pillars in complex stress conditions. We proposed a roadway stability control technology using backwall grouting with high-water rapid hardening material and combined support with bolt and cable anchoring after mining both sides. Our field practices showed that deformation of rock surrounding roadways can be controlled with this technology.

Longwall surface subsidence control by technology of isolated overburden grout injection

Surface subsidence is a typical ground movement due to longwall mining, which causes a series of environmental problems and hazards. In China, intensive coal extractions are commonly operated under dense-populated coalfields, which exacerbates the negative subsequences resulted from surface settlement. Therefore, effective approaches to control the ground subsidence are in urgent need for the Chinese coal mining industry. This paper presents a newly developed subsidence control technology: isolated overburden grout injection, including the theory, technique and applications. Relevant procedures such as injection system design, grouting material selection, borehole layout, grout take estimation and injection process design are proposed. The applicability of this technology has been demonstrated through physical modelling, field measurements, and case studies. Since 2009, the technology has been successfully applied to 14 longwall areas in 9 Chinese coal mines. The ultimate surface subsidence factors vary from 0.10 to 0.15. This method has a great potential to be popularized and performed where longwall mining are implemented under villages and ground infrastructures.

Comparative study of model tests on automatically formed roadway and gob-side entry driving in deep coal mines

Automatically formed roadway(AFR)by roof cutting with bolt grouting(RCBG)is a new deep coal mining technology.By using this technology,the broken roadway roof is strengthened,and roof cutting is applied to cut off stress transfer between the roadway and gob to ensure the collapse of the overlying strata.The roadway is automatically formed owing to the broken expansion characteristics of the collapsed strata and mining pressure.Taking the Suncun Coal Mine as the engineering background,the control effect of this new technology on roadways was studied.To compare the law of stress evolution and the surrounding rock control mechanisms between AFR and traditional gob-side entry driving,a comparative study of geomechanical model tests on the above methods was carried out.The results showed that the new technology of AFR by RCBG effectively reduced the stress concentration of the roadway compared with gob-side entry driving.The side abutment pressure peak of the solid coal side was reduced by 24.3%,which showed an obvious pressure-releasing effect.Moreover,the position of the side abutment pressure peak was far from the solid coal side,making it more beneficial for roadway stability.The deformation of AFR surrounding rock was also smaller than the deformation of the gob-side entry driving by the overload test.The former was more beneficial for roadway stability than the latter under higher stress conditions.Field application tests showed that the new technology can effectively control roadway deformation.Moreover,the technology reduced roadway excavation and avoided resource waste caused by reserved coal pillars.

NUMERICAL SIMULATION ANALYSES ON REINFORCEMENT FUNCTION OF THE TENSIONED AND GROUTED BOLTS

The purpose of the paper is to calculate the equivalent mechanics parameters of reinforced surroundings, which is based on the assume that the reinforcement of bolts is equivalent to the improvement of mechanics parameters of surroundings and combines with site engineering practice. Use numerical simulation analysis to study the reinforcement mechanism of full length bolts, thus to provide theoretical bases for bolting design.

Mechanics Principle and Engineering Application of Split Layer and Bed Separation of Mining Overburden

To control land surface subsidence caused the underground mineral exploitation and the catastrophic phenomena such as serious damage of buildings, waterbodies, cultivated lands, railways, bridges caused by land subsidence, bed separation grouting technology of overburden is put forward. To provide theoretical support for the technology, the characteristics and the mechanics mechanism of mining overburden from layer-split to formation of bed separation are studied. On the basis of elastic sheet board theory, calculation formula of rock sheet deflection is presented, and the mechanics criteria of the separation formation and the calculation formula of bed separation volume are set up. Finally, the applications and technics of bed separation grout technology of mining overburden to control land subsidence in china are introduced.

贵州裸露型岩溶地下河系统污染防治技术——以遵义坪桥地下河系统污染防治工程为例

裸露型岩溶区岩溶强发育、水文地质条件复杂,受污染的地下河系统通道隐蔽性强、污染防治难度大。本文以坪桥地下河系统污染防治工程为例,在近污染源的主径流通道实施“地下水防渗帷幕+污水抽排”工程措施实现近源截排。施工面临岩溶破碎地层易掉块卡埋钻、钻效低及岩溶强发育段浆液扩散距离远等难题。通过配备适宜的钻进工艺,采取纯压式灌浆、水泥砂浆灌填溶洞、低压限量及速凝浆液灌注等灌浆控制措施,保证了工程进度质量,实现了源头治理污染地下水的目的。“近源截排”对类似水文地质条件下地下水污染防治提供可借鉴的地学治理模式。

软土地层三线小角度叠交盾构隧道施工影响规律及位移控制

天津地铁6号线入出段线盾构隧道上穿既有隧道,通过现场实测和数值模拟对既有隧道结构变形规律、变形影响因素、不同变形控制措施的效果进行了研究。结果表明:盾构上穿过程中既有隧道竖向位移整体呈现出隆起-沉降-隆起的变化规律;刀盘距叠交部位断面距离L=2.0D(D为隧道直径)时,叠交部位断面轴力达到最大值,L=0~2.0D时,叠交部位断面弯矩逐渐由L≤0时的横8字形转变为L≥2.0D时的三叶草形;新建隧道与既有隧道的叠交角度在15°~60°、竖向净距小于1.0D时,既有隧道竖向位移受新建隧道影响较大,实际工程中应使叠交角度大于60°,竖向净距大于1.0D;设置支撑台车后,支撑台车影响范围约为2倍台车长度,在影响范围内横断面位移得到控制,但随着支撑台车离开,原来位置处对位移的控制效果逐渐消失;与不注浆相比,深孔注浆加固后既有隧道竖向位移最大值和水平位移最大值分别减小了67.4%、76.0%。

囊袋式注浆对盾构下穿高速铁路路基沉降的控制效果

高铁路基的沉降变形是影响运营安全的重要因素,盾构下穿既有高铁线路施工可诱发高铁路基沉降变形。为有效控制高铁路基沉降,基于数值模拟探究了囊袋式注浆作为高铁路基沉降主动控制措施的有效性。结果表明:注浆囊袋对其周围土体的影响具有局部性,地层等效塑性应变随注浆体埋深的增加而增大,且塑性区厚度通常小于注浆囊袋膨胀厚度的3.0倍。囊袋的埋设深度和膨胀直径对路基抬升整治范围有影响,囊袋埋设越浅其膨胀后对路基抬升的影响效果越明显,且路基表层的隆起变形曲线符合高斯方程。提出了盾构下穿高铁路基时囊袋式注浆控制措施下路基沉降预测模型,可指导盾构下穿高铁路基的沉降控制。

基于离散元法的盾尾同步注浆扩散及参数优化研究

为观察盾构施工中同步注浆扩散规律,并提出注浆参数调控手段,以滨海砂土地层为目标,设计并开展盾尾同步注浆模型试验,获得隧道外侧不同位置浆液扩散规律。在借助试验结果标定离散元模型中各颗粒间接触参数的基础上,建立盾尾同步注浆连续-离散元耦合模型,模拟浆液填充渗透过程,对照试验结果分析导致注浆层厚度差异的主要原因,进而通过调整注浆参数优化浆液填充效果。结果表明:离散元仿真模型中的颗粒运移特性能够有效展示浆液在盾尾间隙及周边土层中的填充、渗透现象;受流动性影响,浆液较易在注浆孔口聚集,而若注浆压力不足,将导致距离注浆孔较远的隧道上、下侧浆液层均匀性不良,通过调整不同部位注浆孔压力配比关系,可有效改善填充效果;注浆层受土层压力影响,隧道上方厚度相对下侧较薄,而侧面浆液在自身重力作用下向下沉积,呈上薄下厚分布。

隧道管棚支护承载特性及支护参数试验研究

为探究隧道管棚注浆钢管不同支护参数对管棚支护承载能力的影响,引入Pasternak双参数模型构建出更符合实际情况的管棚支护力学模型,通过多组室内试验,对管棚在不同注浆钢管管径、壁厚、注浆饱满度及加设钢筋笼条件下的承载能力进行定量研究。研究表明:1)管棚注浆钢管支护参数中,对管棚承载能力的影响排序为:管径>注浆饱满度>壁厚>钢筋笼。2)增大管棚注浆钢管管径可大幅提高管棚的承载能力,相比管径为108 mm的管棚,管径为159、219、299 mm时管棚承载能力分别增大183.58%、398.62%、874.86%。3)管棚钢管注浆不饱满会较大程度削弱管棚的承载能力,钢管注浆饱满度由100%降至75%、50%时,管棚承载能力分别降低29.8%、34.5%,注浆饱满度为50%时管棚的承载能力与未注浆时相差不大。4)管棚钢管壁厚和钢筋笼加设与否对管棚的承载能力影响较小。因此,在实际工程中,可通过增大管棚钢管管径提升管棚的承载能力,通过减小管棚钢管壁厚及不加设钢筋笼节约用钢量。

地聚合物注浆材料的制备工艺及病害公路加固中的应用研究

为提高病害路面修复效率和修复效果,利用矿渣、粉煤灰、偏高岭土、碱激发剂等材料制备一种早期强度高、收缩性小、工作性能优异的地聚合物,并将其应用到实际工程中。结果表明,当采用矿渣∶粉煤灰∶偏高岭土=3∶5∶2制备地聚合物粉料时,碱最佳掺量为8%,碱激发剂最佳模数为1.4,最佳水灰比为0.32;最佳注浆参数为:注浆压力0.6 MPa,注浆孔距为150 cm,注浆量为70~120 kg/m^(2);利用制备的地聚合物对某病害路段进行注浆加固处理,加固完成7 d后,可以将加固路段的平均弯沉值从39.1 mm降至21.8 mm,路面结构得到有效加强,加固效果良好,具有十分明显的社会和工程经济效益。

新研7号和隆跃99挑旗后干物质积累及灌浆特性分析

为探明大穗大粒型小麦品种新研7号、隆跃99挑旗后叶面积衰落、干物质积累和籽粒灌浆特性,在品种展示田中每8~9 d取20个单茎地上部分,测定叶面积、烘干质量;标记同日扬花单穗,每4~5 d一次剥取20穗中部10小穗籽粒,计数后测烘干质量。结果显示,新研7号、隆跃99单茎质量、干物质积累量和花后群体干物质量高于济麦22,叶片衰老慢、功能期长,渐增、快增阶段和最大、平均灌浆速率高于济麦22。说明新研7号、隆跃99具有大穗大粒生理基础,高产栽培要以主茎成穗为主。

底板出水水源判识及快速治理检验技术研究与应用

为了快速治理工作面底板出水,首先通过水化学分析方法判识了主要出水水源为底板砂岩水,底板采动裂隙沟通隐伏断层形成了导水通道。提出了基于地面定向钻的分区域分阶段注浆治理思路,将治理区域划分为回采出水区和物探异常区,针对回采出水区提出分阶段对底板垂向导水通道进行封堵。在停采线前方30 m进行第1阶段注浆,在停采线后方30 m进行第2阶段注浆。在注浆过程中通过分析出水点水质变化以及PQT曲线,对治理效果进行了预评价;治理结束后根据出水量衰减和井下钻探情况验证了治理效果。表明了基于地面定向钻进的分区域分阶段注浆治理技术可以快速有效地封堵底板出水,研究结果为华北型煤田底板砂岩出水治理提供了宝贵经验。