本文關鍵詞：隧道等效彈性振動邊界的建立及精確爆破振動分析　出處：《北京科技大學》2015年博士論文　論文類型：學位論文

  更多相關文章： 巖體隧道 爆破震動 精確動力載荷 彈性振動邊界 沖擊硬化

【摘要】：隧道及地下工程等巖體的掘進開挖多采用爆破的方法。在爆破過程中,部分能量轉(zhuǎn)化為爆破地震波并在巖上介質(zhì)中傳播,當其強度超過一定限度時,就會對圍巖體及既有地表建(構)筑物的內(nèi)部結(jié)構產(chǎn)生影響,此影響可能表現(xiàn)為內(nèi)部介質(zhì)的損傷或破壞。本文圍繞爆破振動的產(chǎn)生方式、傳播規(guī)律及其對圍巖體和建(構)筑物的作用機理展開了較為系統(tǒng)的分析。 (1)通過分析爆破孔內(nèi)爆破氣體壓力變化、炮孔體積擴張、圍巖裂隙發(fā)展和爆破氣體運動規(guī)律等,應用查普曼-柔格模型、氣體狀態(tài)方程以及氣體動力學方程,深入研究了爆破過程中能量的耗散機理,推導了不同爆破階段的載荷計算形式,建立了爆破動力載荷的時程模型,考慮了尺度效應,分析了不同炮孔截面上的載荷變化及爆轟波在孔內(nèi)的反射疊加作用,建立了爆破動力載荷隨時間和炮孔尺寸變化的擬三維載荷模型。 (2)將爆破孔劃分為掏槽孔及存在二次臨空面的工作孔,應用動力梯度理論推導了爆破粉碎區(qū)和爆破碎裂區(qū)的能量衰減程度及其作用范圍�；诖朔治�,將爆破孔、爆破粉碎區(qū)及爆破碎裂區(qū)等效為產(chǎn)生彈性振動的爆破載荷作用邊界(等效彈性振動邊界),并通過聲發(fā)射監(jiān)測的現(xiàn)場爆破相似模擬實驗和掏槽爆破及其它工作孔爆破的數(shù)值模擬分析,對等效爆破載荷作用邊界的范圍及其作用方式進行了界定和驗證。 (3)爆破能量分為炸藥爆炸過程中因化學損耗和氣體噴出所消耗的耗散能、用于隧道圍巖體開挖的有效機械功能及產(chǎn)生爆破振動的振動效應能。本文中考慮了化學損耗及氣體噴出原理,建立了擬三維動力載荷模型,并分析了爆轟壓力下圍巖的粉碎及碎裂機制,界定了等效振動載荷的作用邊界,分別實現(xiàn)了對耗散能和有效機械功能的剔除。 (4)通過砂巖及礫巖的室內(nèi)常規(guī)試驗和分離式霍布金森沖擊試驗,初步確定了不同應變率下的沖擊硬化因數(shù),結(jié)合PFC3D模擬展現(xiàn)了巖石在不同應變率下的破壞過程,并補充了高應變率下的沖擊硬化因數(shù)。之后,基于沖擊硬化因數(shù)對巖石的彈性模量進行了修正,解決了動力分析過程中的沖擊硬化問題。 (5)現(xiàn)場聲發(fā)射及爆破振速的監(jiān)測給出了隧道圍巖體的振動波波長,由此確定了模擬過程中滿足分析精度的最大單元體尺寸。在實際爆破中,受圍巖體非均質(zhì)及振動相互疊加等因素影響,由等效載荷作用邊界方式得出的結(jié)果存在一定偏差,文章基于BP神經(jīng)網(wǎng)絡法的爆破振動場反演,提出了載荷過度系數(shù),對結(jié)果進行了有效修正。最后,結(jié)合大量的現(xiàn)場爆破振動速度的監(jiān)測曲線,采用數(shù)值模擬的方式反演出了彈性振動區(qū)的局部載荷阻尼系數(shù)。 (6)在上述分析的基礎上,本文以燒鍋隧道工程爆破為實例,建立了道爆破開挖及建(構)筑物響應分析模型。通過模擬分析,提取了距爆源不同位置處的振動速度曲線及有效拉應力曲線,建立了彈性振動場,對隧道圍巖體的動力響應特性和振動場內(nèi)既有建(構)筑物的安全穩(wěn)定性進行了分析。
[Abstract]:The use of blasting excavation method of tunnel and underground engineering rock mass excavation. In the blasting process, part of the energy into the blasting seismic wave propagation in the medium and on the rock, when its strength exceeds a certain limit, will be on the surrounding rock body and both the surface construction (structure) affect the internal structure of the building. Effects may be manifested as injury or damage the internal medium. This paper around the blasting vibration, propagation and the rock body and built (structure) mechanism of building out a more systematic analysis.
(1) through the analysis of changes of blasting gas pressure blasting hole, hole volume expansion, rock fracture development and blasting gas movement law, the application of Chapman soft lattice model, gas state equation and gas dynamics equations, in-depth study of the energy dissipation mechanism of blasting process calculation, deduced the different blasting load stage. A process model of blasting dynamic load, considering the scale effect, analyzes the variation of the load of different hole sections of the detonation wave superposition and reflection in the hole, three-dimensional load model of blasting dynamic load with time and hole size change is established.
(2) will be divided into cuthole blasting holes and has two free face working hole, application of dynamic gradient theory is deduced and the blasting blasting crushing zone fragmentation region energy attenuation degree and scope. Based on this analysis, the blasting hole blasting, crushing zone and blasting fragmentation region is equivalent to the boundary blasting load produce elastic vibration (the equivalent elastic vibration boundary), and through numerical simulation and analysis of acoustic emission monitoring of Blasting simulation and blasting hole blasting and other work, the definition and verification of the equivalent blasting load boundary and its mode of action.
(3) the blasting energy dissipation into the explosive process due to the chemical loss and gas discharge energy consumed, for the vibration effect of surrounding rock of tunnel excavation and the effective mechanical function of blasting vibration can be generated. This paper considers the chemical loss and gas discharge principle, a quasi three-dimensional dynamic load model, and analyzes the explosion under the pressure of the surrounding rock crushing and detonation fragmentation mechanism, defines the boundary of equivalent vibration loads, are implemented to remove the energy dissipation and effective mechanical function.
(4) the sandstone and conglomerate laboratory and separation type hob Higginson impact test, impact hardening factor under different strain rates have been determined, with PFC3D simulation show the failure process of rock under different strain rate, and the high strain rate impact hardening factor. Then, elastic modulus the impact factor of rock hardening based on modified to solve the problem of dynamic analysis of impact hardening process.
(5) monitoring the acoustic emission and the velocity of blasting vibration in tunnel surrounding rock wave length, the maximum cell size analysis meet the accuracy of the simulation process. In practical blasting, confining rock heterogeneity and vibration superimposed factors, obtained by the equivalent load boundary mode results there is a certain deviation, the inversion of blasting vibration field based on BP neural network method is proposed, the load over coefficient, the results were corrected effectively. Finally, combining with the blasting vibration velocity monitoring curve of the numerical simulation method of local load damping coefficient of elastic vibration of the performance counter.
(6) on the basis of the above analysis, this paper takes pot tunnel blasting example, established the road of blasting excavation and construction (structure) building response analysis model. Through simulation analysis, extraction of vibration velocity curves at different positions away from the explosion source and the effective tensile stress curve, established the elastic vibration field. The characteristics of vibration and dynamic response of the surrounding rock of the tunnel floor is built (structure) safety and stability of structures are analyzed.

【學位授予單位】：北京科技大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：U455.6

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