  We first formulate, in the framework of effective Lagrangian, the general
form of the effective interactions of the lightest Higgs boson h and a heavier
neutral Higgs boson H in a multi-Higgs system taking account of Higgs mixing
effect. We regard h as the discovered Higgs boson which has been shown to be
consistent with the standard model (SM) Higgs boson. The obtained effective
interactions contain extra parameters reflecting the Higgs mixing effect. Next,
We study the constraints on the anomalous coupling constants of H from both the
requirement of the unitarity of the S matrix and the exclusion bounds on the SM
Higgs boson obtained from the experimental data at the 7--8 TeV LHC. From this
we obtain the available range of the anomalous coupling constants of H, with
which H is not excluded by the yet known theoretical and experimental
constraints. We then study the signatures of H at the 14 TeV LHC. In this
paper, we suggest taking weak-boson scattering and pp to VH* to VVV as
sensitive processes for probing H model independently at the 14 TeV LHC. We
take several examples with the anomalous HVV coupling constants in the
available ranges to do the numerical study. a full tree-level calculation at
the hadron level is given with signals and backgrounds carefully calculated. We
impose a series of proper kinematic cuts to effectively suppress the
backgrounds. It is shown that, in both the VV scattering and the pp to VH* to
VVV processes, H boson can be discovered from the invariant mass distributions
of the final state particles with reasonable integrated luminosity. Especially,
in the pp to VH* to VVV process, the invariant mass distribution of the final
state jets can show a clear resonance peak of H. Finally, we propose several
physical observables from which the values of the anomalous coupling constants
f_W and f_{WW} can be measured experimentally.
