With existing and ongoing large galaxy surveys, new questions in the study of large scale structure need be addressed. It includes the challenge of studying the less dense regions in the cosmic web, such as filaments, as well as the quest for new constraints on cosmological parameters and modified gravity theory. In this talk, I present a weak lensing detection of filaments in the cosmic web, combining data from the KiDS-VIKING-450 survey, the Red Cluster Sequence Lensing Survey and the Canada--France--Hawaii Lensing Survey. I will also present an analysis on the departure from General Relativity in the context of the Hu-Sawicki functional form of f(R) gravity using the DES Y1 cluster abundance data. While these work are motivated by analysis of DES Y1 and KiDS dataset, they are applicable to future surveys, such as LSST and CSST.
