| 摘要: | 本研究以先前胡家豪(2019)研究成果為基礎，探討不同整治工法對於整治效果之影響，並從數值分析結果與參數分析中，了解整治效果之發揮機制以及不同設計參數對應之整治效果。本研究採用簡化逆向岩坡為先前分析模型中，變形與破壞狀況最為嚴重的模型，依照該模型之破壞與變形狀況，規劃採用預力岩錨與全段灌漿之岩釘進行整治，探討整治效果之發揮情形。
研究結果顯示，離心試驗結果中，預力岩錨施加之預力隨重力場提升瞬間而上升，並隨岩石片變形及破壞過程而逐漸下降至一穩定值，岩石片之變形與倒塌狀況較未整治岩坡更為輕微。而就離心試驗中岩釘整治岩坡來說，其變形與破壞區之發展也與未整治岩坡相較輕微。
本研究以離心試驗結果為基礎，建立相同配置之離散元素數值模型。驗證後的數值模型顯示，預力岩錨整治岩坡於岩坡淺層靠近承壓板處有一定範圍受到壓力作用，而隨著坡體逐漸變形或破壞，有更大的區域承受壓力區，此區也可能代表相對穩定區，而緊臨壓力區上方的區域，則有一定範圍之受拉力區，由於岩層抗拉強度較抗壓強度低，此區域可能代表潛在之破壞區。當岩坡開始變形時，亦可以看到岩釘發揮其坡體加勁的效果，使得僅有少部分岩層受到輕微拉力之作用。
此外，數值模型也針對預力岩錨及岩釘設計不同整治參數加以分析，岩錨模型變因包含增加重力場、減少岩錨預力、施打不同岩錨角度及位置。模擬結果顯示，增加重力場時導致原施加之預力不足，與預力減少對於岩坡穩定性均會有打折之效果，施打較不利之岩錨角度會對增加岩坡的破壞與變形狀況，當岩錨施打至較有利位置時，岩坡則相對穩定。岩釘模型變因包含增加重力場、減少岩釘長度、施打不同岩釘角度及位置。增加重力場下的岩釘無法發揮有效整治效果，施打岩釘長度不足時亦會發生嚴重之變形與破壞，岩釘施打角度未來穿過可能的破壞面時，將使岩坡破壞區域明顯提高，施打岩釘的高度有效穿過潛在破壞面時，發生些微變形，但不會產生岩體倒塌破壞。
綜合以上結論可得出在逆向坡使用預力岩錨整治時，岩錨給予岩體的預力以及施打高度位置為較重要之因素。岩釘工法中因為灌漿因素所以施打長度以及施打高度及其重要，能使岩釘有效發揮整治之效果，利用有效分析可能產生潛在破壞面調整所需之參數設定，進而有效發揮整治之效果。
;In this study, the mitigation measures for an anti-dip slope model were investigated through centrifuge tests and discrete element modeling. Based on previous studies that were performed by the same research team, the model anti-dip slope that was deformed most significantly was selected in the current study. The model anti-dip slope was mitigated by applying two measures, which are pre-stressed rock anchor and rock dowel. To investigate the variation of axial force in the pre-stressed rock anchor, a set of strain gauges were also applied onto the rock anchor. During the centrifuge tests, a gravity field of 20g was applied in the testing environment which is the same as the previous study for comparison with the un-mitigated anti-dip slope.
The research results show that in the centrifugal test results, the pre-stressed applied by the pre-stressed rock anchor increases instantaneously with the lifting of the gravity field, and gradually decreases to a stable value with the deformation and failure process of the rock sheet. The deformation and collapse of the rock sheet are relatively stable. Remediation of rock slopes is more minor. For the rock slope rectified by the rock dowel in the centrifugal test, the development of the deformation and damage area is also slightly smaller than that of the unregulated rock slope.
The discrete element models were established to be the same as the centrifuge test configurations. The numerical models were then verified by varying a number of numerical parameters to be comparable with the deformed and collapsed conditions as in the centrifuge tests. Based on the verified pre-stressed anchor model, it was found that the shallow rock layers close to the regions around the anchor plate are under compression modes, as compared to the un-mitigated models. As the rock anchor-mitigated slope deformed, the compression regions were increased, indicating that the potential deformation zones were reduced. On the other hand, the rock dowel-mitigated slope showed that the rock dowel was tensioned once the slope started to deform. However, the tensioned areas in the slope were not as significant as in the un-mitigated model, indicating that the potential collapsed areas were also reduced. A number of parametric studies are planned to be performed regarding the design parameters of the mitigation measures.
In addition, the numerical model also analyzes different remediation parameters for pre-stressed rock anchors and rock dowel designs. The rock anchor model variables include increasing the gravity field, reducing the rock anchor pre-stressed, and applying different rock anchor angles and positions. The simulation results show that when the gravity field is increased, the original pre-stressed will be insufficient, and the reduction of the pre-stressed will have the effect of reducing the stability of the rock slope. The unfavorable rock anchor angle will increase the damage and deformation of the rock slope. , when the rock anchor is applied to a more favorable position, the rock slope is relatively stable. The variation factors of the rock dowel model include increasing the gravity field, reducing the length of the rock dowel, and applying different angles and positions of the rock dowel. Increasing the rock dowel under the gravity field cannot play an effective remediation effect, and severe deformation and damage will occur when the length of the rock dowel is insufficient. When the height of the rock dowel is increased, when the height of the rock dowel effectively passes through the potential failure surface, a slight deformation occurs, but the collapse of the rock mass will not occur.
Based on the above conclusions, it can be concluded that when using pre-stressed rock anchors to rectify the reverse slope, the pre-stressed given to the rock mass by the rock anchor and the position of the applied height are the more important factors. Due to the grouting factor in the rock dowel construction method, the length of the application and the height of the application are very important, so that the rock dowel can effectively exert the effect of remediation, and use the effective analysis of the potential damage surface adjustment. |
