Blasting technique for stabilizing accidentprone slope for sustainable railway route

Konkan Railway has many unstable slopes along the 741 km long route from Roha to Thokur in the states of Maharashtra, Goa and Karnataka in India. Frequent cases of boulder fall, slope failure and landslide used to occur on the track during the rainy season. Such cases have resulted in several severe train accidents, traffic interruptions, loss of lives and assets. Hence the Konkan Railway Corporation deployed several geotechnical measures such as wire-netting, retaining wall, rock bolting and shotcreting for stability enhancement. However, none of these measures proved effective and accidents continued. Finally, the Konkan Railway Corporation decided to redesign the cut-slopes using blasting. Excavation of hard rock for its removal without damaging the existing track (2– 3 m away from the slope) and disrupting the traffic, was a daunting task. An unplanned blast would have resulted in the closure of the route for hours. The present study explains the method in which entire cutting was redesigned by formation of 5 to 2 m wide berms at an interval of 6 m bench height from rail track level using novel direction controlled blasting technique. Further, stability of the cut-slope, before and after exacavation, has been determined using kinematic analysis and 3D numerical modelling. Similar technique can be adopted to widen or stabilize an active transportation route in hills

PREDICTING BLAST-INDUCED GROUND VIBRATIONS IN SOME INDIAN TUNNELS USING DECISION TREE

This study compares three different techniques — decision tree, artificial neural network (ANN) and multivariate regression analysis (MVRA) — for predicting blast-induced ground vibrations in some Indian tunneling projects. The models’ performance was also compared with site-specific conventional predictor equations. A database consisting of 137 vibration records was randomly divided into training and testing sets for model generation. The results indicate that the decision tree is best suited to predicting vibrations. Furthermore, the decision tree suggests that the intensity of near-field ground vibrations is mainly affected by the total charge fired in a round, whereas the intensity of far-field vibrations is governed by maximum charge per delay and charge per hole

Application of logistic regression, CART and random forest techniques in prediction of blast-induced slope failure during reconstruction of railway rock-cut slopes

Drilling and blasting operation is often required to excavate the infrastructure slopes for enhancing their stability or creating space for upgradation. While conducting blasting, there are many incidents of slope failure or rockfall. Thus, proper planning and careful designing of different blasting parameters are essentially required to reduce the incidents of slope failure or rockfall. In the present research, the efficacies of three machine learning (ML) techniques; Logistic Regression (LR), Classification and Regression Tree (CART) and Random Forest (RF) were examined for predicting the blast-induced slope failure (BISF) or blast-induced rockfall during reconstruction of slopes on railway route. 490 databases with thirteen variables were considered for the prediction of BISF. By applying Multicollinearity and LR technique based on minimum Akaike Information Criterion values, the six most influential input parameters were identified. With the selected input datasets, fivefold cross-validation was carried out on randomly selected five sub-groups of datasets using LR tool. Then, the best LR model having the highest prediction rate was selected and with the same training and testing datasets of the selected model, the CART and RF models were also developed. The various performance indices such as correctness, recall rate, precision, specificity, F-beta score, receiver operating characteristics (ROC) and area under the curve (AUC) were calculated to evaluate the developed models' accuracy and applicability. The developed models showed good prediction abilities, with the RF model having highest performance in terms of recall rate (90%), accuracy (96.94%) and F-beta score (0.882). The LR model has higher precision (88.9%) and AUC value (0.96) than CART and RF models. The findings of the research work demonstrate the applicability of all three models in selecting the blast design parameters to prevent BISF during blasting. The use of developed models would result in saving the commuter’s lives, avoiding traffic delays and minimising property damages in similar situations

Directional controlled blasting technique for excavation of unstable slopes along the Konkan Railway route

The paper presents an innovative directional controlled blasting (DCB) technique for excavating unstable slopes along the Konkan railway in India without disturbing the traffic. New empirical formulae for small geometry blasting to estimate burden and throw were developed. A unique sequence of firing and excavation with powder factor varying between 0.04 and 0.39 kg/m3, irrespective of the actual free face, was used for rock blasting. The process controlled the throw of blasted material over the track and resulted in a smooth and stable wall. The slope angle was changed from 80–82 to 45– 47 degrees, and possible wedge, planar and toppling failures were eliminated. No incident of rockfall and slope failure along these slopes has been observed after the stabilization

Innovative Directional Controlled Blasting Technique for Excavation of Unstable Slopes Along a Busy Transportation Route: a Case Study of Konkan Railway in India

Many cases of derailments, train accidents and traffic interruptions due to the slope failure and rockfall have been reported in the past on Konkan Railway trackline because of unstable rock slopes. The authorities installed stability enhancement measures such as wire netting, rock bolting and shotcreting which were found insufficient. The failed geotechnical measures prompted authorities to excavate the unstable slopes. Rock blasting is generally not preferred for the excavation of slopes along the transportation route. Stabilisation and widening of slopes by blasting need closure of the route for a considerable time. Discontinuing traffic on Konkan Railway route was undesirable as it connects two important port cities Mumbai and Mangalore. The paper presents an innovative directional controlled blasting (DCB) technique for excavating three unstable slopes (i.e. cuttings) in hilly terrain without disturbing the traffic. New empirical formulae for small geometry blasting to estimate burden and throw have been developed. A unique sequence of firing and excavation with powder factor varying between 0.04 and 0.39 kg/m3 irrespective of the actual free face was used for rock blasting. The process controlled the throw of blasted material over the track and resulted in a smooth and stable wall. The slope angle has been changed from 80 to 82° to 45–47° and probability of wedge, planar and toppling failures was eliminated. About 100 such accident-prone slopes (52 km cumulative length, 7% of total route) situated at discrete locations along Konkan Railway route were stabilised using the technique. No incident of rockfall and slope failures along these slopes has been observed after the stabilisation

Specific blasting technique for tunnelling in hot zones.

Encountering hot zones while excavating tunnels for hydropower projects in the Himalaya, India, is a challenge for civil engineers. Blasting within the hot rock mass can pose serious threats due to possibility of temperature-induced unintended detonation of explosives. Moreover, the paucity of a suitable rock-blasting method for these hot zones sometimes compels engineers to realign the tunnel. Such a realignment is costly and time-consuming. A temperature of 50–98°C was encountered while excavating the rock mass for head race tunnel of Karchham–Wangtoo Hydro-Electric Project, Himachal Pradesh, India. The Directorate General of Mine Safety, India, suggests that blastholes with temperature greater than 80°C must not be charged and blasted. Similarly, the use of electric or non-electric detonators is discouraged above 70°C because of premature detonation. Hence excavation works were suspended for tunnel construction. A unique drill and blast method has been adopted for blasting the hot strata in the tunnel. The technique described in this study can be easily followed in similar situations for tunnel-rock excavation

Evaluating the sustainability of a hydropower project in the Himalayas: A case study for resolving legal disputes in tribunals

Land use controversies often dog the construction of hydroelectric projects. Many important projects are battling in the tribunals because of Geo-environmental concerns. The paucity of scientific studies objectively investigating the litigations further aggravates the un solvability of the disputes. The SawraKuddu Hydroelectric project, India, became a subject of litigation when project affected persons filed a suit in the National Green Tribunal questioning the sustainability of the built environment. The litigants petitioned that the additional adit's blasting vibrations can trigger the landslide of slip zone, and Thana village situated above it. The petitioners further claimed that vibrations had cracked the houses. They also asserted degradation in the apple cultivation due to tunnel construction. The tribunal took a stern note of the petition and banned the construction activities. The tribunal further ruled that a scientific investigation must be conducted to ascertain the cause of petitioners' claims. The study results revealed that the vibrations originating from adit excavation are insignificant and cannot destabilize the slip zone. The high fluctuation of annual rainfall and tectonic strain were deemed responsible for the differential settlement of foundations and cracks in the houses. The horticulture study indicated that the physiological processes of apple crops were normal. The study's findings convinced the tribunal, and construction activities were resumed, resulting in the disputed 111 MW project's commissioning. Many run-of-the-river hydroelectric projects in the world are battling similar litigations addressed in the present study. A similar objective methodology is a need for the hour to resolve other hydroelectric projects' sustainability issues. The study findings will pave the path for the swift resolution of land disputes related to similar project