層間泥縫剪裂試驗模擬技術之開發

Development of Experimental Technology for Shear behavior of bedding-shear

嚴中廷(Chung-Ting Yen)

指導教授 ： 楊長義

淡江大學/工學院/土木工程學系碩士班/碩士(2017年)

https://doi.org/10.6846/TKU.2017.00152

摘要

順向坡的特性是具順層的結構，且因受到層間之錯動(bedding shear)常存在層間摩擦剪動的「泥縫(seam)」，其被蹍碎後的顆粒常比上下母岩更細微化或成黏土等級，因此其摩擦角常又比原來母岩更低、且更易吸水。因此，本文主要模擬在受剪下細粒泥縫內剪裂帶(shear band)之破裂擴展過程行為，接著探討地層在被推擠剪動所產生的層間剪裂帶其強度衰減之趨勢。
結果得致下列主要結論：(1) 本文設計出可模擬剪裂帶破裂過程之儀器，以利觀察其剪動破壞過程。係利用長形剪裂儀搭配上泥縫剪裂壓克力模具，與找尋可模擬出泥縫剪動破壞之材料填入模具內，觀測剪裂帶內裂縫出現時機、長度、寬度與個數等等發展變化。文中亦使用自行開發出剪裂帶裂縫發展程式進行分析，最後搭配自行改良之針入度試驗儀與無圍壓縮試驗，模擬此泥縫層因剪動破壞後力學折減之情形。(2) 測試結果發現到黏土類材料所發生剪裂帶帶寬相較於麵粉+砂材料而言就較於狹窄，其窄帶區內細微裂縫相互連接產生出大變形之滑移帶(主要位移剪裂面)，黏土材料特性偏向於脆-塑性，較適合完整模擬出剪裂帶(shear zone)與滑移帶(slip zone)之發展與演進。(3) 本試驗重複模擬剪裂帶破壞過程，利用剪裂帶裂縫發展分析程式記錄下裂縫發展(幾何關係)與剪位移之關係，統計出初期剪動時(約2~3%)，裂縫尚未發展出，剪位移到達5%時開始有些微張力裂縫出現，裂縫長度、寬度、數量也會隨著剪位移的增加而在增長，剪位移達5%至持續剪動完畢時，裂縫長度、寬度、數量會不再明顯增加且趨於穩定。裂縫在發展時的確會因為剪位移之增加其碎形維度也跟著上升，也說明著裂縫破裂程度越來越嚴重，裂縫發展到一定之剪位移量時就不會因為剪位移增加其裂縫碎形維度繼續跟著上升，到破壞結束時碎形維度趨於穩定。(4) 試驗得知剪裂帶的確會因為受剪動產生泥縫，強度會伴隨著下降，當尚未剪動(Us=0mm)時也就是圍岩(硬岩)時之強度，UCS=19.05Kpa，受剪後產生剪裂帶時(Us=6mm)，此刻強度從原來19.05Kpa降至11.95Kpa，持續受剪到較大之剪位移(Us=12mm)，慢慢開始出現主要位移剪裂面，此時強度以衰減到剩下4.86Kpa，可應證隨著剪動距離增加而強度越來越弱。

關鍵字

層間剪動 ； 順向坡 ； 泥縫 ； 剪裂帶 ； 漸進破壞 ； 碎形維度

並列摘要

Consequent slope is a smooth layer structure and because by the bedding shear between the layers, there is often present interlayer friction shear move called "seam", which the particle broken after often than upper and lower rock more or a level of fine clay, so often surpasses the original rock friction angle lower and more absorbent.Therefore, this paper mainly simulate the behavior of the shear band in the shear zone,then we discuss the trend of the strength of the interlayer shear zone caused by the push shear.
The results obtained to the following main conclusions:(1) In this paper, we can design the instrument to simulate the fracture process of the shear zone to observe the shear failure process. The use of long-shaped splitting apparatus with the upper split acrylic mold, and to find out the material can be simulated out of the shear fracture of the material into the mold, observe the cracks in the cracks in the emergence of time, length, width and number of development changes. We also use the self-developed shear crack development program to analyze the situation, and finally with the self-improvement of the penetration tester and no compression test to simulate the slit due to shear damage after the mechanical reduction of the situation. (2) The results show that the banding bandwidth of the clastic material is narrower than that of the flour + sand material, and the fine cracks in the narrow zone are connected with each other to produce a large deformation slip zone (main displacement shear surface) , The characteristics of clay material tend to brittle - plastic, more suitable for a complete simulation of the shear zone and slip zone with the development and evolution. (3) The relationship between fracture development (geometric relation) and shear displacement is recorded by using the fracturing development analysis program of shear zone, and the initial shear rate (about 2 ~ 3%) is calculated. The fracture has not yet developed when the shear displacement reaches 5%, some micro-tension cracks begin to appear. The length, width and quantity of the crack will increase with the increase of the shear displacement. The shear length will reach 5% until the continuous shear is completed. The length, width and quantity will no longer significantly increase and become stable. Cracks in the development of the shear will do because of the increase in the size of the fractal dimension also followed the rise also shows that the degree of fracture rupture more and more serious, the development of cracks to a certain amount of shear when the shear will not increase its fracture fractal dimension Continue to follow the rise, to the end of the destruction of the fragile dimension tends to be stable. (4) It was found that the shear zone would be due to the slippage caused by the shear, and the strength would be accompanied by a decrease in the strength of the surrounding rock (hard rock) when it had not been sheared (Us = 0 mm), UCS = 19.05Kpa, (Us = 6mm), the intensity decreased from the original 19.05Kpa to 11.95Kpa, the shear was cut to the larger shear (Us = 12mm), and the main displacement shear surface began to appear slowly, At this point the intensity to decay to the remaining 4.86Kpa, can be expected with the shear distance increases and the intensity is getting weaker.

並列關鍵字

Bedding Shear ； Dip slope ； Slip zone ； shear zone ； Progressive damage ； Fractal

參考文獻

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